Remove viz PyPI selector and other minor maintenance

[hakonanes]

Description of the change

• Remove deprecated viz PyPI selector
• Allow RTD to build PDF again (after they introduced intentional failure in previously passing LaTeX builds for a reason I didn't understand)
• Use `trusted publisher' option in publishing workflow
• Improve color control in keyword argument to GeometricalKikuchiPatternSimulation.as_collections()

Progress of the PR

• [n/a] Docstrings for all functions
• Unit tests with pytest for all lines
• Clean code style by running black via pre-commit

For reviewers

• The PR title is short, concise, and will make sense 1 year later.
• New functions are imported in corresponding __init__.py.
• New features, API changes, and deprecations are mentioned in the unreleased
  section in CHANGELOG.rst.
• New contributors are added to release.py, .zenodo.json and
  .all-contributorsrc with the table regenerated.