⬆️ Update sphinx requirement from <9,>=8 to >=8,<10

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@v8.0.0...v9.0.0)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-version: 9.0.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

pyproject.toml

@@ -38,7 +38,7 @@ dependencies = [
     "markdown-it-py~=4.0",
     "mdit-py-plugins~=0.5",
     "pyyaml",
-    "sphinx>=8,<9",
+    "sphinx>=8,<10",
 ]
 
 [project.urls]