fixed forward decl

include/core/Ref.hpp

@@ -3,10 +3,9 @@
 
 #include "Variant.hpp"
 #include "GodotGlobal.hpp"
+#include "../Reference.hpp"
 
 namespace godot {
-class Reference;
-class Object;
 
 // Replicates Godot's Ref<T> behavior
 // Rewritten from f5234e70be7dec4930c2d5a0e829ff480d044b1d.