Bump sphinx from 4.5.0 to 5.0.0 in /docs

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 4.5.0 to 5.0.0.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/5.x/CHANGES)
- [Commits](https://github.com/sphinx-doc/sphinx/compare/v4.5.0...v5.0.0)

---
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==4.5.0
+sphinx==5.0.0
 sphinx_rtd_theme==1.0.0
 readthedocs-sphinx-search==0.1.2
 jinja2<3.1.0