Ignore extra_unused_type_parameters clippy lint in test

    error: type parameter goes unused in function definition
     --> tests/test_autotrait.rs:1:20
      |
    1 | fn assert_send_sync<T: Send + Sync>() {}
      |                    ^^^^^^^^^^^^^^^^
      |
      = help: consider removing the parameter
      = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#extra_unused_type_parameters
      = note: `-D clippy::extra-unused-type-parameters` implied by `-D clippy::all`

tests/test_autotrait.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::extra_unused_type_parameters)]
+
 fn assert_send_sync<T: Send + Sync>() {}
 
 #[test]