Avoid adding ready services for outdated peers

If a service becomes ready but it's for a connection to an outdated
peer, drop it.

zebra-network/src/peer_set/set.rs

@@ -352,7 +352,8 @@ where
 
     /// Check busy peer services for request completion or errors.
     ///
-    /// Move newly ready services to the ready list, and drop failed services.
+    /// Move newly ready services to the ready list if they are for peers with supported protocol
+    /// versions, otherwise they are dropped. Also drop failed services.
     fn poll_unready(&mut self, cx: &mut Context<'_>) {
         loop {
             match Pin::new(&mut self.unready_services).poll_next(cx) {
@@ -364,7 +365,10 @@ where
                     trace!(?key, "service became ready");
                     let cancel = self.cancel_handles.remove(&key);
                     assert!(cancel.is_some(), "missing cancel handle");
-                    self.ready_services.insert(key, svc);
+
+                    if svc.version() >= self.minimum_peer_version.current() {
+                        self.ready_services.insert(key, svc);
+                    }
                 }
 
                 // Unready -> Canceled