Update sphinx requirement from ~=7.1 to ~=7.2 in /requirements (#828)

Updates the requirements on [sphinx](https://github.com/sphinx-doc/sphinx) to permit the latest version.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES)
- [Commits](sphinx-doc/sphinx@v7.1.0...v7.2.0)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Chris Wagner <jwag.wagner@gmail.com>

requirements/docs.txt

@@ -1,4 +1,4 @@
 Pallets-Sphinx-Themes~=2.1
-Sphinx~=7.1
+Sphinx~=7.2
 sphinx-issues==3.0.1
 packaging