build(deps): bump sphinx in /docs in the minor-and-patch group (#628)

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


Updates `sphinx` from 8.1.3 to 8.2.1
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/v8.2.1/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v8.1.3...v8.2.1)

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

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

@@ -1,4 +1,4 @@
 furo==2024.8.6
-sphinx==8.1.3
+sphinx==8.2.1
 sphinx-click==6.0.0
 myst_parser==4.0.1