build(deps): bump sphinx from 7.2.6 to 7.3.7 in /requirements

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 7.2.6 to 7.3.7.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v7.2.6...v7.3.7)

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

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

requirements/requirements_doc.txt

@@ -9,7 +9,7 @@ pyvista[jupyter]==0.43.7
 vtk==9.3.0
 
 # Documentation dependencies
-Sphinx==7.2.6
+Sphinx==7.3.7
 numpydoc==1.7.0
 ansys-sphinx-theme==0.15.2
 sphinx-copybutton==0.5.2