Avoid formatting dyn* test as rustftm doesn't understand it yet and just deletes code

src/tools/miri/tests/pass/dyn-star.rs

@@ -1,5 +1,8 @@
 #![feature(dyn_star)]
 #![allow(incomplete_features)]
+#![feature(custom_inner_attributes)]
+// rustfmt destroys `dyn* Trait` syntax
+#![rustfmt::skip]
 
 use std::fmt::{Debug, Display};