BUGFIX: Unit test failed due to changed error message

IntegrationTests/CallbackTest.cs

@@ -95,6 +95,6 @@ public class CallbackTest {
         Assert.Throws<ArgumentException>(() => {
                 FitConnect.Subscriber.VerifyCallback(_callbackSecret, _request);
             })
-            .Message.Should().Be("Request is not authentic");
+            .Message.Should().Be("Verified request does not match authentication");
     }
 }