Bump sphinx from 7.2.5 to 7.2.6

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 7.2.5 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@v7.2.5...v7.2.6)

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

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

requirements/requirements_docs.txt

@@ -3,7 +3,7 @@ imageio==2.31.3
 numpydoc==1.4.0
 imageio-ffmpeg==0.4.7
 Sphinx<7.2.0; python_version == '3.8'
-Sphinx==7.2.5; python_version >= '3.9'
+Sphinx==7.2.6; python_version >= '3.9'
 sphinx-autobuild==2021.3.14
 sphinxcontrib-napoleon==0.7
 sphinxcontrib-websupport==1.2.4