Upgrade to Grace Database Migration Plugin 6.1.0-RC1

Closes gh-693

Author: rainboyan

gradle/grails.versions.toml

@@ -1,7 +1,7 @@
 [plugins]
 asset-pipeline = "6.1.0-RC1"
 cache = "6.1.0-RC1"
-database-migration = "6.1.0-M3"
+database-migration = "6.1.0-RC1"
 fields = "6.1.0-RC1"
 geb = "6.1.0-RC1"
 hibernate = "2023.1.0-RC1"