Make setup.py auto recognize release version

Currently, we set the release version in setup.py manually.
This might introduce a gap in version number between github repo and PyPi.
It would be beter if the version auto-increments when we have a new release.

It seems like there are several ways to do this:
- Create a self-triggered github actions when version number is updated in pyproject.toml
- This will require a new setup.py routine, but I think it is a better way
- Use "auto-increment and publish" github actions (there are several, but seems unmaintained?)
- Use other packaging tools