Fix RID cannot be string formatted

Author: billuo

core/variant/variant_op.cpp

@@ -465,6 +465,7 @@ void Variant::_register_variant_operators() {
 	register_string_modulo_op(Color, Variant::COLOR);
 	register_string_modulo_op(StringName, Variant::STRING_NAME);
 	register_string_modulo_op(NodePath, Variant::NODE_PATH);
+	register_string_modulo_op(::RID, Variant::RID);
 	register_string_modulo_op(Object, Variant::OBJECT);
 	register_string_modulo_op(Callable, Variant::CALLABLE);
 	register_string_modulo_op(Signal, Variant::SIGNAL);