chore(deps-dev): bump pygithub from 2.7.0 to 2.8.1

Bumps [pygithub](https://github.com/pygithub/pygithub) from 2.7.0 to 2.8.1.
- [Release notes](https://github.com/pygithub/pygithub/releases)
- [Changelog](https://github.com/PyGithub/PyGithub/blob/main/doc/changes.rst)
- [Commits](PyGithub/PyGithub@v2.7.0...v2.8.1)

---
updated-dependencies:
- dependency-name: pygithub
  dependency-version: 2.8.1
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]