Update pygithub requirement from ~=2.8 to ~=2.9

Updates the requirements on [pygithub](https://github.com/pygithub/pygithub) to permit the latest version.
- [Release notes](https://github.com/pygithub/pygithub/releases)
- [Changelog](https://github.com/PyGithub/PyGithub/blob/main/doc/changes.rst)
- [Commits](PyGithub/PyGithub@v2.9.0...v2.9.1)

---
updated-dependencies:
- dependency-name: pygithub
  dependency-version: 2.9.1
  dependency-type: direct:production
...

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

Author: dependabot[bot]

pyproject.toml

@@ -20,7 +20,7 @@ dev = [
      "sync-with-uv~=0.5.0",
 ]
 maint = [
-      "pygithub~=2.8",
+      "pygithub~=2.9",
       "ruamel-yaml~=0.19",
       "Unidecode~=1.3",
 ]