message: Fix ack test race
diff: @@ -817,7 +817,7 @@ mod jetstream {
  }
  client.flush().await.unwrap();
  - tokio::time::sleep(Duration::from_millis(100)).await;
  + tokio::time::sleep(Duration::from_millis(500)).await;
  let info = consumer.info().await.unwrap();
  assert_eq!(info.num_ack_pending, 8);
  