Bump furo from 2025.9.25 to 2025.12.19 (#2875)

Bumps [furo](https://github.com/pradyunsg/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](pradyunsg/furo@2025.09.25...2025.12.19)

---
updated-dependencies:
- dependency-name: furo
  dependency-version: 2025.12.19
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pyproject.toml

@@ -37,7 +37,7 @@ Tidelift = "https://tidelift.com/subscription/pkg/pypi-marshmallow?utm_source=py
 [project.optional-dependencies]
 docs = [
   "autodocsumm==0.2.14",
-  "furo==2025.9.25",
+  "furo==2025.12.19",
   "sphinx-copybutton==0.5.2",
   "sphinx-issues==5.0.1",
   "sphinx==8.2.3",