cargo fmt

Signed-off-by: Yoshua Wuyts <yoshuawuyts@gmail.com>

benches/mutex.rs

@@ -85,8 +85,8 @@ mod async_std {
 mod parking_lot {
     extern crate test;
 
-    use std::sync::Arc;
     use parking_lot::Mutex;
+    use std::sync::Arc;
     use std::thread;
     use test::Bencher;