fix build

Author: mythz

src/ServiceStack.Redis/Support/Diagnostic/TrackingRedisClientProxy.cs

@@ -1,4 +1,4 @@
-#if !(NETSTANDARD2_0 || NETSTANDARD2_1)
+#if !(NETSTANDARD2_0 || NETSTANDARD2_1 || NET6_0)
 using System;
 using System.Reflection;
 using System.Runtime.Remoting.Messaging;

src/ServiceStack.Redis/Support/Diagnostic/TrackingRedisClientsManager.cs

@@ -1,4 +1,4 @@
-#if !(NETSTANDARD2_0 || NETSTANDARD2_1)
+#if !(NETSTANDARD2_0 || NETSTANDARD2_1 || NET6_0)
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;