Replace pkg_resources with packaging library (removes setuptools dependency) for spotfire-python 2.1.3

[vrane-tibco]

with Latest setuptools getting error while creating spk

ModuleNotFoundError: No module named 'pkg_resources'

This issue is only applicable for spotfire-python 2.1.x, latest spotfire-python releases already handled this issue

[vrane-tibco]

Fixed this by using packaging package instead pkg_resources (#59)