Bump Java baseline from 17 to 21 for Grails 8#1216

jamesfredley wants to merge 1 commit into8.0.xapache/grails-spring-security:8.0.xfrom

fix/java-21-baseline-8.0.xapache/grails-spring-security:fix/java-21-baseline-8.0.xCopy head branch name to clipboard