Flask 2 support

[dividedmind]

AppMap fails with Flask 2 with error:

  File "/usr/local/lib/python3.9/site-packages/appmap/flask.py", line 146, in <module>
    flask.cli.call_factory = wrap_cli_fn(flask.cli.call_factory)
AttributeError: module 'flask.cli' has no attribute 'call_factory'

[apotterri]

Fixed by #186