Bump furo from 2025.7.19 to 2025.9.25 (#2842)

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]

doc/requirements.txt

@@ -1,3 +1,3 @@
 -e .
 sphinx~=8.1
-furo==2025.7.19
+furo==2025.9.25