message: Flush on publish ack await
diff: use crate::jetstream::account::Account;
  use crate::jetstream::publish::PublishAck;
  use crate::jetstream::response::Response;
  -use crate::{Client, Error};
  +use crate::{Client, Command, Error};
  use bytes::Bytes;
  use futures::{Future, StreamExt, TryFutureExt};
  use serde::de::DeserializeOwned;
  @@ -804,6 +804,7 @@ pub struct PublishAckFuture {
  impl PublishAckFuture {
  async fn next_with_timeout(mut self) -> Result<PublishAck, Error> {
  + self.subscription.sender.send(Command::TryFlush).await.ok();
  let next = tokio::time::timeout(self.timeout, self.subscription.next())
  .await
  .map_err(|_| std::io::Error::new(ErrorKind::TimedOut, "acknowledgment timed out"))?;
  