Bump sphinx from 5.1.1 to 6.1.3 in /docs

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 5.1.1 to 6.1.3.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES)
- [Commits](sphinx-doc/sphinx@v5.1.1...v6.1.3)

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

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

Author: dependabot[bot]

docs/requirements.txt

@@ -1,4 +1,4 @@
 furo==2022.12.7
-sphinx==5.1.1
+sphinx==6.1.3
 sphinx-click==4.3.0
 myst_parser==0.18.1