Add github action to auto publish to PyPI

[lbdreyer]

Rather than having to manually upload the built distribution to PyPI, it would be good to automate it.

For more details, see https://packaging.python.org/guides/publishing-package-distribution-releases-using-github-actions-ci-cd- workflows/

ASSUMED INCLUDED automated builds + build checks

[HGWright]

The effort comes from making this a reusable workflow.