Suppress dead code warning in test of unit struct remote derive

    error: struct `RemoteSelf` is never constructed
       --> test_suite/tests/test_gen.rs:425:12
        |
    425 |     struct RemoteSelf;
        |            ^^^^^^^^^^
        |
    note: the lint level is defined here
       --> test_suite/tests/test_gen.rs:5:9
        |
    5   | #![deny(warnings)]
        |         ^^^^^^^^
        = note: `#[deny(dead_code)]` implied by `#[deny(warnings)]`

test_suite/tests/test_gen.rs

@@ -422,6 +422,7 @@ fn test_gen() {
 
     #[derive(Serialize, Deserialize)]
     #[serde(remote = "Self")]
+    #[allow(dead_code)]
     struct RemoteSelf;
 
     #[derive(Serialize, Deserialize)]