Trusted Publishing and better social media publishing

[Zeitsperre]

Pull Request Checklist:

• This PR addresses an already opened issue (for bug fixes / features)
  • This PR fixes #xyz
• Tests for the changes have been added (for bug fixes / features)
  • (If applicable) Documentation has been added / updated (for bug fixes / features)
• CHANGES.rst has been updated (with summary of main changes)
  • Link to issue (:issue:number) and pull request (:pull:number) has been added

What kind of change does this PR introduce?

• Replaces the token-based authentication for uploads to PyPI/TestPyPI with the Trusted Publishing feature
• Implement deployment environments as a security measure when running workflows that upload to PyPI/TestPyPI
• Fixes the Mastodon-publishing action so that excess quotation marks (") are removed
• Mastodon publishing now uses chuhlomin/render-template to format toots.

Does this PR introduce a breaking change?

Not really. The publishing workflows are no longer dependent on authentication tokens, so these should be removed from the repository secrets and voided.

Other information:

• https://docs.pypi.org/trusted-publishers/
• https://docs.github.com/en/actions/deployment/targeting-different-environments/using-environments-for-deployment
• https://github.com/chuhlomin/render-template