Bump sphinx from 5.0.2 to 7.2.6 in /docs

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 5.0.2 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@v5.0.2...v7.2.6)

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

Signed-off-by: dependabot[bot] <support@github.com>

docs/requirements.txt

@@ -1,4 +1,4 @@
-sphinx==5.0.2
+sphinx==7.2.6
 sphinx-click==4.2.0
 sphinxcontrib_bibtex==2.4.2
 furo==2022.6.21