Upgrade unit test to use pytest

[artemp]

pytest test/python_tests                                                        
================================================================= test session starts ==================================================================
platform darwin -- Python 3.11.0, pytest-7.2.1, pluggy-1.0.0
rootdir: /Users/artemp/projects/mapnik-consulting/python-mapnik
collected 360 items                                                                                                                                    

test/python_tests/agg_rasterizer_integer_overflow_test.py ..                                                                                     [  0%]
test/python_tests/box2d_test.py ......                                                                                                           [  2%]
test/python_tests/buffer_clear_test.py ..                                                                                                        [  2%]
test/python_tests/cairo_test.py .........                                                                                                        [  5%]
test/python_tests/color_test.py ...                                                                                                              [  6%]
test/python_tests/compare_test.py .......                                                                                                        [  8%]
test/python_tests/compositing_test.py ..........                                                                                                 [ 10%]
test/python_tests/copy_test.py .....                                                                                                             [ 12%]
test/python_tests/csv_test.py ........................................                                                                           [ 23%]
test/python_tests/datasource_test.py ...........                                                                                                 [ 26%]
test/python_tests/datasource_xml_template_test.py .                                                                                              [ 26%]
test/python_tests/extra_map_props_test.py ..                                                                                                     [ 27%]
test/python_tests/feature_id_test.py ....                                                                                                        [ 28%]
test/python_tests/feature_test.py ........                                                                                                       [ 30%]
test/python_tests/filter_test.py ....................                                                                                            [ 36%]
test/python_tests/fontset_test.py .                                                                                                              [ 36%]
test/python_tests/geojson_plugin_test.py ......                                                                                                  [ 38%]
test/python_tests/geometry_io_test.py ................                                                                                           [ 42%]
test/python_tests/grayscale_test.py .                                                                                                            [ 42%]
test/python_tests/image_filters_test.py ..                                                                                                       [ 43%]
test/python_tests/image_test.py .............................                                                                                    [ 51%]
test/python_tests/image_tiff_test.py ..................                                                                                          [ 56%]
test/python_tests/introspection_test.py .                                                                                                        [ 56%]
test/python_tests/json_feature_properties_test.py .                                                                                              [ 56%]
test/python_tests/layer_buffer_size_test.py .                                                                                                    [ 57%]
test/python_tests/layer_modification_test.py .                                                                                                   [ 57%]
test/python_tests/layer_test.py .                                                                                                                [ 57%]
test/python_tests/load_map_test.py ...                                                                                                           [ 58%]
test/python_tests/map_query_test.py .........                                                                                                    [ 61%]
test/python_tests/mapnik_logger_test.py .                                                                                                        [ 61%]
test/python_tests/mapnik_test_data_test.py .                                                                                                     [ 61%]
test/python_tests/markers_complex_rendering_test.py ..                                                                                           [ 62%]
test/python_tests/memory_datasource_test.py .                                                                                                    [ 62%]
test/python_tests/multi_tile_raster_test.py .                                                                                                    [ 62%]
test/python_tests/object_test.py ...........                                                                                                     [ 65%]
test/python_tests/ogr_and_shape_geometries_test.py .                                                                                             [ 66%]
test/python_tests/ogr_test.py ........                                                                                                           [ 68%]
test/python_tests/palette_test.py ..                                                                                                             [ 68%]
test/python_tests/parameters_test.py .......                                                                                                     [ 70%]
test/python_tests/pdf_printing_test.py .                                                                                                         [ 71%]
test/python_tests/pickling_test.py ...                                                                                                           [ 71%]
test/python_tests/png_encoding_test.py .........                                                                                                 [ 74%]
test/python_tests/pngsuite_test.py ..                                                                                                            [ 75%]
test/python_tests/projection_test.py ....                                                                                                        [ 76%]
test/python_tests/query_test.py ..                                                                                                               [ 76%]
test/python_tests/query_tolerance_test.py .                                                                                                      [ 76%]
test/python_tests/raster_colorizer_test.py ....                                                                                                  [ 78%]
test/python_tests/raster_symbolizer_test.py ......                                                                                               [ 79%]
test/python_tests/render_grid_test.py .........                                                                                                  [ 82%]
test/python_tests/render_test.py ...........                                                                                                     [ 85%]
test/python_tests/reprojection_test.py ......                                                                                                    [ 86%]
test/python_tests/save_map_test.py ..                                                                                                            [ 87%]
test/python_tests/shapefile_test.py .........                                                                                                    [ 90%]
test/python_tests/shapeindex_test.py .                                                                                                           [ 90%]
test/python_tests/sqlite_rtree_test.py ..                                                                                                        [ 90%]
test/python_tests/sqlite_test.py ......................                                                                                          [ 96%]
test/python_tests/style_test.py .                                                                                                                [ 97%]
test/python_tests/topojson_plugin_test.py ....                                                                                                   [ 98%]
test/python_tests/webp_encoding_test.py ......                                                                                                   [100%]

================================================================= 360 passed in 15.93s =================================================================
artemp@sunra python-mapnik %