build(deps): bump sphinx from 5.3.0 to 7.1.2 in /requirements

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 5.3.0 to 7.1.2.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v5.3.0...v7.1.2)

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

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

requirements/docs.txt

@@ -1,4 +1,4 @@
-sphinx ==5.3.0
+sphinx ==7.1.2
 myst-parser ==1.0.0
 nbsphinx ==0.9.3
 pandoc ==2.3