Update sphinx requirement from <=7.1 to <=7.2.6

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.rst)
- [Commits](sphinx-doc/sphinx@v0.1.61611...v7.2.6)

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

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

pyproject.toml

@@ -43,7 +43,7 @@ dev = [
     "pytest-black",
     "pytest-asyncio",
     "pytest-pydocstyle",
-    "sphinx<=7.1", #https://github.com/sphinx-doc/sphinx/issues/11662
+    "sphinx<=7.2.6", #https://github.com/sphinx-doc/sphinx/issues/11662
     "sphinx-autobuild",
     "sphinx-copybutton",
     "sphinx-design",