Use Simpler Release Process

[tvhong]

Notes

I find that the proposed git-flow is an overkill for our simple project. I propose using a single main branch and bump2version for version release instead. Please let me know what you think.

Please also note that gitflow-avh is now deprecated: https://github.com/petervanderdoes/gitflow-avh.

[tvhong]

There are a few drawbacks of my proposed process:

• Cannot add changelogs to README before publish to PyPI.
• No validation step before publishing (e.g., by running GitHub CI validations).

I also learned that GitHub Actions can publish directly to PyPI. Maybe we should adopt that workflow.