Fix error due to deletion of impl::Display

src/api/policies/instance/instance.rs

@@ -56,6 +56,6 @@ mod instance_policies_schema_test {
             .unwrap();
 
         let schema = test_instance.instance_policies_schema().await.unwrap();
-        println!("{}", schema);
+        println!("{:?}", schema);
     }
 }