Bump sphinx from 5.3.0 to 7.3.6 in /docs

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 5.3.0 to 7.3.6.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v5.3.0...v7.3.6)

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

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

docs/requirements.txt

@@ -1,4 +1,4 @@
 furo==2022.12.7
 myst-parser==0.18.1
-sphinx==5.3.0
+sphinx==7.3.6
 sphinx-autobuild==2021.3.14