Bump the python-packages group across 1 directory with 2 updates (#2950)

Bumps the python-packages group with 2 updates in the / directory: [black](https://github.com/psf/black) and [furo](https://github.com/pradyunsg/furo).


Updates `black` from 26.3.1 to 26.5.1
- [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/26.3.1...26.5.1)

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: 26.5.1
  dependency-type: direct:development
  update-type: version-update:semver-minor
  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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pyproject.toml

@@ -63,7 +63,7 @@ dev = [
     "pytest-xdist>=2.2.1",
     "pytest-asyncio>=1.2.0",
     "beautifulsoup4>=4.8.1",
-    "black==26.3.1",
+    "black==26.5.1",
     "blacken-docs==1.20.0",
     "pytest-timeout>=1.4.2",
     "trustme>=0.7",
@@ -72,7 +72,7 @@ dev = [
     "ruff>=0.16.0",
     # docs
     "Sphinx==7.4.7",
-    "furo==2025.9.25",
+    "furo==2025.12.19",
     "sphinx-autobuild",
     "codespell>=2.2.5",
     "sphinx-copybutton",