[MNT] Update sphinx requirement (#1457)

Updates the requirements on [sphinx](https://github.com/sphinx-doc/sphinx) to permit the latest version.

Updates `sphinx` 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@v0.1.61611...v7.3.7)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-type: direct:production
  dependency-group: python-packages
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pyproject.toml

@@ -116,7 +116,7 @@ binder = [
     "jupyterlab",
 ]
 docs = [
-    "sphinx<7.3.0",
+    "sphinx<7.4.0",
     "sphinx-design",
     "sphinx-version-warning",
     "sphinx_issues",