Update grails monorepo to v6.0.0 (#544)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

gradle.properties

@@ -4,7 +4,7 @@ datastoreVersion=8.0.0
 gebVersion=2.3
 gparsVersion=1.2.1
 grailsVersion=6.0.0-RC1
-grailsGradlePluginVersion=6.0.0-RC1
+grailsGradlePluginVersion=6.0.0
 groovyVersion=3.0.11
 h2Version=1.4.200
 hibernateDatastoreVersion=8.0.0
@@ -20,7 +20,7 @@ neo4jDriverVersion=4.4.12
 neo4jVersion=3.5.35
 objenesisVersion=3.2
 picocliVersion=4.7.1
-pluginGrailsVersion=6.0.0-RC1
+pluginGrailsVersion=6.0.0
 projectVersion=8.0.1-SNAPSHOT
 seleniumSafariDriverVersion=3.14.0
 seleniumVersion=3.14.0