Bump sphinx from 3.5.3 to 4.3.2

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.5.3 to 4.3.2.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/4.x/CHANGES)
- [Commits](https://github.com/sphinx-doc/sphinx/commits/v4.3.2)

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

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

Author: dependabot[bot]

docs/requirements.txt

@@ -1,3 +1,3 @@
-Sphinx==3.5.3
+Sphinx==4.3.2
 sphinx-autoapi==1.7.0
 sphinx-material==0.0.32