Update godot_interfaces.rst

One too many open curly bracket "{".

Wrong
        public void PrintMe() {

Correct
        public void PrintMe()

tutorials/best_practices/godot_interfaces.rst

@@ -504,7 +504,7 @@ accesses:
             Child.MyMethod();
         }
 
-        public void PrintMe() {
+        public void PrintMe()
         {
             GD.Print(GetClass());
         }