Bump furo from 2025.9.25 to 2025.12.19 (#831)

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
...

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

Author: dependabot[bot]

pyproject.toml

@@ -40,7 +40,7 @@ dependencies = [
 ulid = ["python-ulid"]
 docs = [
     "autodoc_pydantic==2.2.0",
-    "furo==2025.9.25",
+    "furo==2025.12.19",
     "ipython==9.3.0",
     "myst_parser==4.0.1",
     "nbsphinx==0.9.8",