Fix standards check

Author: EmandM

com.unity.netcode.gameobjects/Tests/Runtime/Transports/UnityTransportConnectionTests.cs

@@ -5,6 +5,9 @@
 using NUnit.Framework;
 using Unity.Netcode.TestHelpers.Runtime;
 using Unity.Netcode.Transports.UTP;
+#if HOSTNAME_RESOLUTION_AVAILABLE
+using Unity.Networking.Transport;
+#endif
 using UnityEngine;
 using UnityEngine.TestTools;
 using static Unity.Netcode.RuntimeTests.UnityTransportTestHelpers;