Bump rdoc from 6.0.1 to 6.0.4
Bump rdoc from 6.0.1 to 6.0.4

Bumps [rdoc](https://github.com/ruby/rdoc) from 6.0.1 to 6.0.4.
- [Release notes](https://github.com/ruby/rdoc/releases)
- [Changelog](https://github.com/ruby/rdoc/blob/master/History.rdoc)
- [Commits](https://github.com/ruby/rdoc/compare/v6.0.1...v6.0.4)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
coreyja/glassy-collections,coreyja/glassy-collections,coreyja/glassy-collections