test: add raw_ref_op to failing test

Signed-off-by: Mirko Adzic <adzicmirko97@gmail.com>

Author: Mirko-A

tests/nonstandard_style.rs

@@ -6,6 +6,7 @@
 #![deny(nonstandard_style)]
 #![allow(dead_code)]
 #![cfg_attr(USE_RUSTC_FEATURES, feature(lint_reasons))]
+#![cfg_attr(USE_RUSTC_FEATURES, feature(raw_ref_op))]
 
 use pin_init::*;