Update grails monorepo to v5.1.1

Author: renovate-bot

gradle.properties

@@ -7,7 +7,7 @@ githubSlug=grails/grails-testing-support
 githubBranch=2.3.x
 developers=Jeff Brown,James Kleeh
 grailsGradlePluginVersion=5.1.0
-grailsVersion=5.0.3
+grailsVersion=5.1.1
 grailsDocsVersion=5.0.0.RC1
 asyncVersion=4.0.0
 groovyVersion=3.0.7