You could use a git pre-commit hook to more easily execute the script that sets the version number

See the attached .7z for a simple example (the pre-commit bash script is “…/.git/hooks/pre-commit”).

Just commit after making some changes to the top level .py as you would normally do before any versioning, and see how git automatically calls the bash script which in turn calls a python script to update version.py (which is automatically added to the committed files).