Bump gh-pages from 5.0.0 to 6.1.0 in /docs

Bumps [gh-pages](https://github.com/tschaub/gh-pages) from 5.0.0 to 6.1.0.
- [Release notes](https://github.com/tschaub/gh-pages/releases)
- [Changelog](https://github.com/tschaub/gh-pages/blob/main/changelog.md)
- [Commits](tschaub/gh-pages@v5.0.0...v6.1.0)

---
updated-dependencies:
- dependency-name: gh-pages
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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