add volatile again

LiteNetLib/NetManager.cs

@@ -169,7 +169,7 @@ private struct IncomingData
         private readonly Dictionary<IPEndPoint, ConnectionRequest> _requestsDict;
         private readonly ReaderWriterLockSlim _peersLock;
         private volatile NetPeer _headPeer;
-        private int _connectedPeersCount;
+        private volatile int _connectedPeersCount;
         private readonly List<NetPeer> _connectedPeerListCache;
         private NetPeer[] _peersArray;
         private readonly PacketLayerBase _extraPacketLayer;