add mqtt label to mqtt-handler-test

ragconnect.tests/src/test/java/org/jastadd/ragconnect/tests/MqttHandlerTest.java

@@ -22,6 +22,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  * @author rschoene - Initial contribution
  */
 @Tag("New")
+@Tag("mqtt")
 public class MqttHandlerTest {
 
   @Test