Bump furo from 2025.7.19 to 2025.9.25 in /docs (#696)

Bumps [furo](https://github.com/pradyunsg/furo) from 2025.7.19 to 2025.9.25.
- [Release notes](https://github.com/pradyunsg/furo/releases)
- [Changelog](https://github.com/pradyunsg/furo/blob/main/docs/changelog.md)
- [Commits](pradyunsg/furo@2025.07.19...2025.09.25)

---
updated-dependencies:
- dependency-name: furo
  dependency-version: 2025.9.25
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

docs/requirements.txt

@@ -1,6 +1,6 @@
 aiohttp==3.12.15
 autodoc-pydantic==2.2.0
-furo==2025.7.19
+furo==2025.9.25
 linkify-it-py==2.0.3
 matplotlib==3.10.6
 myst-nb==1.3.0