Prohibit PyPI uploads for the local versions (not the releases)

[nolar]

Following #4, disable the local versions (0.1.dev2+g123456) to be uploaded to PyPI, as PyPI does not accept them (log):

Uploading kopf-0.1.dev9+g21a7230-py3-none-any.whl
HTTPError: 400 Client Error: '0.1.dev9+g21a7230' is an invalid value for Version. Error: Can't use PEP 440 local versions. See https://packaging.python.org/specifications/core-metadata for url: https://upload.pypi.org/legacy/

Sadly, the PYPI uploads can only be tested on the master branch, i.e. after the merges.

[zincr]

🤖 zincr found 0 problems , 0 warnings

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