More tooling upgrades

[jodal]

• Run CI and build docs on Ubuntu 24.04
• Move tox config to pyproject.toml
• Split dev deps into multiple groups
• Doc why setuptools is needed
• Bump pillow to 11.0.0
• Allow newer defusedxml
• Allow newer feedparser
• Bump httpx to 0.28.1
• Bump lxml to 5.3.0
• Bump pytz to 2024.2
• Bump sentry-sdk to 2.19.2
• Bump setuptools to 75.6.0

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.66%. Comparing base (13cb909) to head (f31d0d5).
Report is 14 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #600   +/-   ##
=======================================
  Coverage   61.66%   61.66%           
=======================================
  Files          52       52           
  Lines        2165     2165           
=======================================
  Hits         1335     1335           
  Misses        830      830           

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