worldMessage.targetable=false (#7802)

turret would try to attack worldMessage but cant hit it
so why not combine privileged with targetable(

core/src/mindustry/content/Blocks.java

@@ -5861,6 +5861,8 @@ public class Blocks{
 
         worldMessage = new MessageBlock("world-message"){{
             requirements(Category.logic, BuildVisibility.editorOnly, with());
+            
+            targetable = false;
             privileged = true;
         }};