Update MockedGroupChannel.cs

test/Discord.Net.Tests.Unit/MockedEntities/MockedGroupChannel.cs

@@ -16,6 +16,8 @@ namespace Discord
 
         public ulong Id => throw new NotImplementedException();
 
+        public string RTCRegion => throw new NotImplementedException();
+
         public Task<IAudioClient> ConnectAsync(bool selfDeaf = false, bool selfMute = false, bool external = false)
         {
             throw new NotImplementedException();