fix: Correct clippy lint suggestion part tres

Author: bryantbiggs

crates/shim/src/synchronous/monitor.rs

@@ -83,10 +83,7 @@ impl Monitor {
             topic: topic.clone(),
         };
         self.subscribers.insert(id, subscriber);
-        self.topic_subs
-            .entry(topic)
-            .or_insert_with(Vec::new)
-            .push(id);
+        self.topic_subs.entry(topic).or_default().push(id);
         Ok(Subscription { id, rx })
     }