Bump github-buttons from 2.27.0 to 2.28.0

Bumps [github-buttons](https://github.com/buttons/github-buttons) from 2.27.0 to 2.28.0.
- [Commits](buttons/github-buttons@v2.27.0...v2.28.0)

---
updated-dependencies:
- dependency-name: github-buttons
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]