Ignore unused ignore attribute warning in some configurations

test_suite/tests/compiletest.rs

@@ -1,6 +1,7 @@
 #[cfg_attr(target_os = "emscripten", ignore)]
 #[rustversion::attr(not(nightly), ignore)]
 #[cfg_attr(miri, ignore)]
+#[allow(unused_attributes)]
 #[test]
 fn ui() {
     let t = trybuild::TestCases::new();