Fix test_rainbow_highlighting gate

Author: lnicola

crates/ide/src/syntax_highlighting/tests.rs

@@ -958,7 +958,7 @@ pub struct Struct;
 
 #[test]
 #[cfg_attr(
-    all(unix, not(target_pointer_width = "64")),
+    not(all(unix, target_pointer_width = "64")),
     ignore = "depends on `DefaultHasher` outputs"
 )]
 fn test_rainbow_highlighting() {