Meta: Dev/test environment speedups

[jherland]

Making use of newer and faster tools to speed up our test runs and improve the developer experience:

• ruff to replace pylint and black.
• uv to replace pip.

Tasks

• [x] Introduce ruff (PR #424)
• [x] Configure ruff to replace pylint (PR #425)
• [x] Remove pylint (PR #426)
• [x] Simplify lint pipeline to only run once (instead of once per Python version) (added to PR #426)
• [x] Configure ruff to replace black (PR #427)
• [x] Remove black (PR #427)
• [x] Introduce uv (added via nox[uv] in PR #432)
• [x] Use uv instead of pip where applicable (PR #432):
  • [x] in Nox sessions
  • [x] wherever we invoke pip our test suite
  • [x] use uv with fallback to pip in our install_deps logic.