Bump sphinx from 7.2.5 to 7.2.6 in /requirements

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 7.2.5 to 7.2.6.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v7.2.5...v7.2.6)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements/docs.txt

@@ -1,4 +1,4 @@
 # Install this project in editable mode, so that its package metadata can be queried
 -e .
-Sphinx==7.2.5
+Sphinx==7.2.6
 sphinx-rtd-theme==1.3.0