Change condition for is_terminated in Zip

The condition for `is_terminated` in the `FusedStream` impl for `Zip` should check if either child stream has terminated. Otherwise, one stream may be polled even after it has been terminated if the other has not.

futures-util/src/stream/stream/zip.rs

@@ -64,7 +64,7 @@ where
     St2: Stream,
 {
     fn is_terminated(&self) -> bool {
-        self.stream1.is_terminated() && self.stream2.is_terminated()
+        self.stream1.is_terminated() || self.stream2.is_terminated()
     }
 }