Updated the remapping for subscription to reflect the removal of "uns…

…tamped" from "ros2_controllers"

ref: https://github.com/ros-controls/ros2_controllers/blob/57c50e584e33b316dd64801916cf6d951e0cff5b/tricycle_controller/CHANGELOG.rst#L33

urdf/wheel/diffdrive.gazebo.xacro

@@ -13,7 +13,7 @@
       <xacro:if value="${use_gazebo}">
         <plugin filename="libgz_ros2_control-system.so" name="gz_ros2_control::GazeboSimROS2ControlPlugin">
           <ros>
-            <remapping>diff_drive_controller/cmd_vel_unstamped:=cmd_vel</remapping>
+            <remapping>diff_drive_controller/cmd_vel:=cmd_vel</remapping>
             <remapping>diff_drive_controller/odom:=odom</remapping>
           </ros>
           <parameters>$(find ${config_file_package})/${config_file_path}</parameters>