Add release workflow on github release creation

[eugenetriguba]

This adds a workflow to Github Actions for creating a PyPI release when a GitHub release is created. The motivation for this is so that I would be able to handle #70.

In GitHub, this would require the PYPI_TOKEN secret being setup in the repository settings under Settings > Secrets and Variables > New Repository Secret.

This secret can be created via PyPI API Tokens: https://pypi.org/help/#apitoken. In particular, once the token is created:

To use an API token:
Set your username to __token__
Set your password to the token value, including the pypi- prefix

Poetry uses a format of POETRY_PYPI_TOKEN_<pypi repo name> so POETRY_PYPI_TOKEN_PYPI is the PyPI token for the official PyPI repository: https://python-poetry.org/docs/repositories/#configuring-credentials. It seems it handles sending along the username of __token__ for you.

[Zeitsperre]

@eugenetriguba

Have you considered trying out the Trusted Publisher approach to this? I've been adopting this in a bunch of the projects I maintain, and I find it to be a nicer alternative than managing API Tokens.

e.g. https://github.com/Ouranosinc/xclim/blob/master/.github/workflows/publish-pypi.yml

[eugenetriguba]

@Zeitsperre Oh that is neat, I hadn't seen that before. Appreciate the mention, I'll give it a look 👍