Release v6.0.0-RC1

What's Changed

• Upgrade Grails Cache Redis Plugin and Prepare for New Grails 6.x Release by @sbglasius in #9
• Try fix publishing by @matrei in #10
• ci: restore ci branch triggers by @matrei in #11
• Publish with Java 11, since we're on Grails 6.x by @sbglasius in #12
• Post review fixes by @sbglasius in #13

New Contributors

• @sbglasius made their first contribution in #9
• @matrei made their first contribution in #10

Full Changelog: https://github.com/grails-plugins/grails-cache-redis/commits/v6.0.0-RC1