Bump the python-packages group with 3 updates

Bumps the python-packages group with 3 updates: [black](https://github.com/psf/black), [sphinx](https://github.com/sphinx-doc/sphinx) and [furo](https://github.com/pradyunsg/furo).


Updates `black` from 25.11.0 to 25.12.0
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](https://github.com/psf/black/compare/25.11.0...25.12.0)

Updates `sphinx` from 7.4.7 to 9.1.0
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES.rst)
- [Commits](https://github.com/sphinx-doc/sphinx/compare/v7.4.7...v9.1.0)

Updates `furo` from 2025.9.25 to 2025.12.19
- [Release notes](https://github.com/pradyunsg/furo/releases)
- [Changelog](https://github.com/pradyunsg/furo/blob/main/docs/changelog.md)
- [Commits](https://github.com/pradyunsg/furo/compare/2025.09.25...2025.12.19)

---
updated-dependencies:
- dependency-name: black
  dependency-version: 25.12.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
  dependency-group: python-packages
- dependency-name: sphinx
  dependency-version: 9.1.0
  dependency-type: direct:development
  update-type: version-update:semver-major
  dependency-group: python-packages
- dependency-name: furo
  dependency-version: 2025.12.19
  dependency-type: direct:development
  update-type: version-update:semver-minor
  dependency-group: python-packages
...

Signed-off-by: dependabot[bot] <support@github.com>

pyproject.toml

@@ -61,14 +61,14 @@ dev = [
     "pytest-xdist>=2.2.1",
     "pytest-asyncio>=1.2.0",
     "beautifulsoup4>=4.8.1",
-    "black==25.11.0",
+    "black==25.12.0",
     "blacken-docs==1.20.0",
     "pytest-timeout>=1.4.2",
     "trustme>=0.7",
     "cogapp>=3.3.0",
     # docs
-    "Sphinx==7.4.7",
-    "furo==2025.9.25",
+    "Sphinx==9.1.0",
+    "furo==2025.12.19",
     "sphinx-autobuild",
     "codespell>=2.2.5",
     "sphinx-copybutton",