chore(gateway): don't log WouldBlock on WARN (#6984)

This mirrors what we do on the clients, there is no need to log
`WouldBlock` on `WARN` as those can happen during normal operation.

rust/gateway/src/eventloop.rs

@@ -17,6 +17,7 @@ use futures_bounded::Timeout;
 use phoenix_channel::{PhoenixChannel, PublicKeyParam};
 use std::collections::BTreeSet;
 use std::convert::Infallible;
+use std::io;
 use std::net::IpAddr;
 use std::task::{Context, Poll};
 use std::time::Duration;
@@ -72,6 +73,9 @@ impl Eventloop {
                     self.handle_tunnel_event(event);
                     continue;
                 }
+                Poll::Ready(Err(e)) if e.kind() == io::ErrorKind::WouldBlock => {
+                    continue;
+                }
                 Poll::Ready(Err(e)) => {
                     tracing::warn!("Tunnel error: {e}");
                     continue;