build(deps): bump sphinx (#731)

Bumps the minor-and-patch group with 1 update in the /docs directory: [sphinx](https://github.com/sphinx-doc/sphinx).


Updates `sphinx` from 9.0.0 to 9.0.4
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/v9.0.4/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v9.0.0...v9.0.4)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-version: 9.0.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: minor-and-patch
...

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

Author: dependabot[bot]

docs/requirements.txt

@@ -1,4 +1,4 @@
 furo==2025.9.25
-sphinx==9.0.0
+sphinx==9.0.4
 sphinx-click==6.2.0
 myst_parser==4.0.1