Remove unnecessary clone

Type is `Copy`, no need for clone.

Author: tcharding

src/key.rs

@@ -796,7 +796,7 @@ mod test {
         let pk1 = PublicKey::from_slice(
             &hex!("0241cc121c419921942add6db6482fb36243faf83317c866d2a28d8c6d7089f7ba"),
         ).unwrap();
-        let pk2 = pk1.clone();
+        let pk2 = pk1;
         let pk3 = PublicKey::from_slice(
             &hex!("02e6642fd69bd211f93f7f1f36ca51a26a5290eb2dd1b0d8279a87bb0d480c8443"),
         ).unwrap();