Introduce release automation

[funkyfuture]

Adding a CITATION.cff (#44) would make more sense if the release process was at least partly automated, to not forget to keep version information in parity. delb recently progressed in this regard, i think fttomh these measures would make sense here:

• introduce a Justfile with a release recipe
  • that makes use of https://github.com/delb-xml/cff-from-621
• using the build-and-inspect-python-package Github Action
  • possibly deriving the Python versions to test against in the workflows
• employing trusted publishing directly from a workflow to the PyPI

creating Github releases as a bonus is nerve-consuming, but attaining attention is the only meaning there is in late-stage capitalism.