add namespace given lack of system import

tools/test-proxy/Azure.Sdk.Tools.TestProxy.Tests/SanitizerTestExample.cs

@@ -61,7 +61,7 @@ namespace Azure.Sdk.Tools.TestProxy.Tests
 
             session.Session.Sanitize(registeredSanitizer);
             var newBody = Encoding.UTF8.GetString(session.Session.Entries[0].Response.Body);
-            Console.WriteLine(newBody);
+            System.Console.WriteLine(newBody);
             Assert.Contains("REDACTED", newBody);
         }    
     }