Ignore PrivateDns module each time it upgrades (#12798)

Author: Y-Sindo

src/SignalR/SignalR.Test/TestController.cs

@@ -70,6 +70,7 @@ public void RunPsTestWorkflow(
                 {"Microsoft.Resources", null},
                 {"Microsoft.Features", null},
                 {"Microsoft.Authorization", null},
+                {"Microsoft.PrivateDns", null},
                 {"Microsoft.Network", null}
             };
             var providersToIgnore = new Dictionary<string, string>