Github actions need validation for the version bump

[m4sc0]

I've had this once or twice now that I forgot to update the __init__.py file that contains the version number. This is used in the pypi-publish workflow which is the last step in the pipeline before publishing, at that point a PR has been merged, a release created and tagged. That's not a lot to fix but it gets on my nerves so I wanna add another workflow that checks before merging into master if the __init__.py file has been modified.