message: refactor(client): fix unused Pin import without http2
diff: @@ -4,7 +4,9 @@ use std::future::Future;
  use futures_util::FutureExt;
  use tokio::sync::{mpsc, oneshot};
  -use crate::common::{task, Pin, Poll};
  +use crate::common::{task, Poll};
  +#[cfg(feature = "http2")]
  +use crate::common::Pin;
  pub(crate) type RetryPromise<T, U> = oneshot::Receiver<Result<U, (crate::Error, Option<T>)>>;
  pub(crate) type Promise<T> = oneshot::Receiver<Result<T, crate::Error>>;
  