build(deps): bump dnsruby from 1.61.7 to 1.61.9 in /docs

Bumps [dnsruby](https://github.com/alexdalitz/dnsruby) from 1.61.7 to 1.61.9.
- [Release notes](https://github.com/alexdalitz/dnsruby/releases)
- [Changelog](https://github.com/alexdalitz/dnsruby/blob/master/RELEASE_NOTES.md)
- [Commits](https://github.com/alexdalitz/dnsruby/compare/v1.61.7...v1.61.9)

---
updated-dependencies:
- dependency-name: dnsruby
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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