fix rudp. Server couldn't receive (On.Modify) and (On.Open) event aft…

…er accepted.

fix rudp. Server couldn't receive (On.Modify) and (On.Open) event after accepted.

src/rudp/partials/RUDP.ServerTo.cs

@@ -373,6 +373,10 @@ private void ContentUpdate()
 
                                 // invoke new client
                                 On.OnAccept?.Invoke(null, client);
+
+                                // start client connection callback
+                                client._on?.OnModify(null, _socket);
+                                client._on?.OnOpen(null, null);
                             }
                         });