[AltServer] Fixes NetworkConnection strong reference cycle

WirelessConnection.nwConnection.stateUpdateHandler maintains strong reference to WirelessConnection, resulting in strong reference cycle. To break it, we now explicitly set stateUpdateHandler to nil when disconnecting.

AltServer/Connections/WirelessConnectionHandler.swift

@@ -144,5 +144,10 @@ private extension WirelessConnectionHandler
         connection.disconnect()
         
         self.disconnectionHandler?(connection)
+        
+        if let networkConnection = connection as? NetworkConnection
+        {
+            networkConnection.nwConnection.stateUpdateHandler = nil
+        }
     }
 }