fix: remove debug line in KeepAlive timeout check handler

Author: viglucci

UnityRSocket/Assets/Viglucci/UnityRSocket/Runtime/KeepAlive/KeepAliveHandler.cs

@@ -46,8 +46,7 @@ public void Start()
         private void TimeoutCheck()
         {
             if (Done) return;
-            
-            Debug.Log("TimeoutCheck");
+
             long now = DateTimeOffset.Now.ToUnixTimeMilliseconds();
             long noKeepAliveDurationMillis = now - _lastReceivedMillis;
             if (noKeepAliveDurationMillis >= _keepAliveTimeoutDurationMillis)