This should be the last release candidate.

• Adds 1.21.6 support by @VideoGameSmash12 in https://github.com/VideoGameSmash12/Librarian/pull/10
• Updates Adventure to 4.22.0 by @VideoGameSmash12 in https://github.com/VideoGameSmash12/Librarian/pull/20

Full Changelog: https://github.com/VideoGameSmash12/Librarian/compare/v3.0-rc4...v3.0-rc5