why: release.yml iterates print-packages dynamically (reads all
packages/*/pyproject.toml) and passes each name to smoke, but sphinx-autodoc-
docutils, sphinx-autodoc-sphinx, and sphinx-autodoc-pytest-fixtures were absent
from the smoke runners dict and argparse choices list, causing exit code 2.
what:
- Add smoke_sphinx_autodoc_docutils(), smoke_sphinx_autodoc_sphinx(), and
  smoke_sphinx_autodoc_pytest_fixtures() functions to package_tools.py
- Register all three in the runners dict in smoke()
- Add all three to argparse choices for the smoke subcommand
- Add all three to the matrix targets in tests.yml