Update Grails Gradle Plugin to 5.2.6 (#12872)

Author: puneetbehl

grails-bom/plugins.properties

@@ -1,7 +1,7 @@
 gorm.hibernate5=7.3.0
 gorm.mongodb=7.3.0
 gorm.neo4j=7.3.0
-grails-gradle-plugin=5.2.5
+grails-gradle-plugin=5.2.6
 cache=5.0.1
 rxjava=1.1.1
 rxjava2=2.0.0