build(deps-dev): update sphinx requirement from <8.2 to <9.2

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...v9.1.0)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-version: 9.1.0
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pyproject.toml

@@ -24,7 +24,7 @@ toxgen = [
 docs = [
     "gevent",
     "shibuya",
-    "sphinx<8.2",
+    "sphinx<9.2",
     "sphinx-autodoc-typehints[type_comments]>=2.3.0",
     "typing-extensions",
 ]