Bump sphinx from 3.5.4 to 4.0.2

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.5.4 to 4.0.2.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/4.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v3.5.4...v4.0.2)

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

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

Author: dependabot[bot]

requirements-dev.txt

@@ -1,5 +1,5 @@
 ipython==7.16.1
-Sphinx==3.5.4
+Sphinx==4.0.2
 sphinx-autobuild==0.7.1
 sphinxcontrib-fulltoc==1.2.0
 nbsphinx==0.7.1