update unsound dev dependency and fix mapped_futures memory leak

Author: StoicDeveloper

futures-util/Cargo.toml

@@ -48,7 +48,7 @@ pin-project-lite = "0.2.6"
 futures = { path = "../futures", features = ["async-await", "thread-pool"] }
 futures-test = { path = "../futures-test" }
 tokio = "0.1.11"
-futures-timer = "3.0.2"
+futures-timer = "3.0.3"
 
 [package.metadata.docs.rs]
 all-features = true

futures-util/src/stream/mapped_futures/mod.rs

@@ -167,9 +167,7 @@ impl<K: Hash + Eq, Fut> MappedFutures<K, Fut> {
         if let Some(task) = self.set().take(key) {
             unsafe {
                 if (*task.future.get()).is_some() {
-                    let cell = task.future.get();
-                    cell.drop_in_place();
-                    cell.write(None);
+                    *task.future.get() = None;
                     self.inner.unlink(Arc::as_ptr(&task.inner));
                     return true;
                 }