Publish to PyPI when a new tag is created

[swaroopch]

• Should be consistent with https://github.com/swaroopch/edn_format/blob/master/CONTRIBUTING.md
• https://github.com/actions/starter-workflows/blob/main/ci/python-publish.yml
• https://docs.github.com/en/free-pro-team@latest/actions/guides/building-and-testing-python#publishing-to-package-registries

[swaroopch]

Looks like it worked - https://github.com/swaroopch/edn_format/runs/1365596695 :)