Resolve wildcard_imports pedantic clippy lint in test suite

error: usage of wildcard import
       --> test_suite/tests/test_gen.rs:901:9
        |
    901 |     use super::*;
        |         ^^^^^^^^ help: try: `super::Deserialize`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#wildcard_imports
        = note: `-D clippy::wildcard-imports` implied by `-D clippy::pedantic`

test_suite/tests/test_gen.rs

@@ -898,7 +898,7 @@ impl Drop for RemotePackedNonCopyDef {
 /// Regression tests for <https://github.com/serde-rs/serde/issues/2371>
 #[allow(dead_code)]
 mod static_and_flatten {
-    use super::*;
+    use serde::Deserialize;
 
     #[derive(Deserialize)]
     struct Nested;