Update distutils patch to monkeypatch all paths from sys.path to ensure that distutils is never imported except from the same path as setuptools. Assert that 'distutils' is not already in sys.modules.

Run docs build as part of CI

Moved distutils' doc for setup-keywords into our doc to document all supported keywords

- Fix upload test on systems that blocks MD5
- Add SHA2-256 and Blake2b-256 digests based on new Warehous and twine
  specs.
Signed-off-by: Christian Heimes <christian@python.org>

Support attr directive with static evaluation

Fix an RST link typo in the dev guide

distutils.tests now saves/restores warnings filters to leave them
unchanged. Importing tests imports docutils which imports
pkg_resources which adds a warnings filter.

📝 Document setup.cfg-only possibilities