Update cookiecutter template, fix CI builds

[Zeitsperre]

Pull Request Checklist:

• This PR addresses an already opened issue (for bug fixes / features)
  • This PR fixes #xyz
• (If applicable) Documentation has been added / updated (for bug fixes / features).
• (If applicable) Tests have been added.
• This PR does not seem to break the templates.
• CHANGELOG.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?

• Updated the cookiecutter template to the latest commit
• Updated versions of many GitHub Actions and Python dependencies
• Removed coveralls from the CI dependencies
• Added pre-commit hooks for vulture (dead code) and codespell (typos)
• Grammatical errors have been addressed in several docstrings and in notebooks

Does this PR introduce a breaking change?

Not really. New hooks required some fixes (mostly typos).

Other information:

mypy will require some moderate effort to convert the code base to adopt. The hook is staged, but not enabled. No major urgency around this.

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[Zeitsperre]

@aulemahal This seems to be complaining about the French catalogues, but running $ make findfrench/translate seems to be failing for me. Was there an API change?

[aulemahal]

The new babel (2.17) automatically adds a "python-brace-format" comment to the po file when the translated string is a f-string. This is to be used in an upcoming (not implemented yet) check that would ensure the translation uses the same f-string variables than the source. Which sounds useful!

So I updated the po file and the translations, and pinned babel >= 2.17.