build(deps): bump sphinx from 6.1.3 to 7.2.6 in /docs

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 6.1.3 to 7.2.6.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v6.1.3...v7.2.6)

---
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

@@ -1,3 +1,3 @@
 furo==2023.3.27
-sphinx==6.1.3
+sphinx==7.2.6
 sphinx-click==4.1.0