fix: busy loop on shutdown

src/client.rs

@@ -1437,8 +1437,11 @@ where
 
     fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         self.inner.maybe_close_connection_if_no_streams();
+        let had_streams_or_refs = self.inner.has_streams_or_other_references();
         let result = self.inner.poll(cx).map_err(Into::into);
-        if result.is_pending() && !self.inner.has_streams_or_other_references() {
+        // if we had streams/refs, and don't anymore, wake up one more time to
+        // ensure proper shutdown
+        if result.is_pending() && had_streams_or_refs && !self.inner.has_streams_or_other_references() {
             tracing::trace!("last stream closed during poll, wake again");
             cx.waker().wake_by_ref();
         }