More GitHub Actions Cleanup for 4.0

[Cleptomania]

Cleans up some remaining GitHub Actions things ahead of 4.0 development.

Primarily:

• Switches to the more streamlined uv setup for build/publish to PyPi instead of the old PEP 517 build/twine publish. Makes the setup in line with all other actions workflows we have now.
• Combines the GitHub and PyPi release into one workflow, triggered on creation of a new tag. Creating a tag will do both the pypi release and the GitHub release, and generate the release notes from the commit for the GitHub release.
• Removes to test.pypi.org release workflow, as it's outdated and unused, if we want to bring it back for testing something, can do a fresh copy of the prod one.
• Consolidates the code quality inspections and doc build back into one workflow. These are still separate jobs so they can run in parallel though.
• Maybe fixes the Discord status embed that was broken because of naming changes in the workflows, unsure if there are other problems with that though.