Bump sphinx from 5.2.3 to 7.2.6 in /extra_requirements

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 5.2.3 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@v5.2.3...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]>

extra_requirements/requirements-docs.txt

@@ -7,7 +7,7 @@ gitpython==3.1.40
 graphviz==0.20.1
 nbsphinx==0.9.3
 recommonmark==0.7.1
-sphinx==5.2.3
+sphinx==7.2.6
 sphinx_rtd_theme==1.0.0
 sphinxcontrib_applehelp==1.0.2
 sphinxcontrib_devhelp==1.0.2