Upgrade to Grace Geb Plugin 6.3.0-M1

Closes gh-919

Author: rainboyan

gradle/grails.versions.toml

@@ -3,7 +3,7 @@ asset-pipeline = "6.3.0-M1"
 cache = "6.3.0-M1"
 database-migration = "6.3.0-SNAPSHOT"
 fields = "6.3.0-M1"
-geb = "6.2.0"
+geb = "6.3.0-M1"
 hibernate = "2023.3.0-SNAPSHOT"
 scaffolding = "6.3.0-M1"