THRIFT-5600: rust lib to upgrade to edition 2021
Client: rs
Patch: Jiayu Liu

This closes #2628
diff --git a/lib/rs/src/server/multiplexed.rs b/lib/rs/src/server/multiplexed.rs
index b447d38..f6811a4 100644
--- a/lib/rs/src/server/multiplexed.rs
+++ b/lib/rs/src/server/multiplexed.rs
@@ -271,10 +271,10 @@
             _: &mut dyn TInputProtocol,
             _: &mut dyn TOutputProtocol,
         ) -> crate::Result<()> {
-            let res = self
-                .invoked
-                .compare_and_swap(false, true, Ordering::Relaxed);
-            if res {
+            let res =
+                self.invoked
+                    .compare_exchange(false, true, Ordering::Relaxed, Ordering::Relaxed);
+            if res.is_ok() {
                 Ok(())
             } else {
                 Err("failed swap".into())