fixing warehouse SDF

Author: SteveMacenski

nav2_minimal_tb4_sim/worlds/warehouse.sdf

@@ -15,12 +15,10 @@
       filename="gz-sim-user-commands-system"
       name="gz::sim::systems::UserCommands">
     </plugin>
-  <xacro:unless value="$(arg headless)">
     <plugin
       filename="gz-sim-scene-broadcaster-system"
       name="gz::sim::systems::SceneBroadcaster">
     </plugin>
-  </xacro:unless>
     <plugin
       filename="gz-sim-sensors-system"
       name="gz::sim::systems::Sensors">