Changed the state_publihser type to the robot_state_publihser type because it is deprecated.

launch/description.launch

@@ -14,11 +14,11 @@
             frame:=$(arg model_frame)
             mesh:=$(arg model_mesh)" />
 
-    <node pkg="robot_state_publisher" type="state_publisher" name="state_publisher">
+    <node pkg="robot_state_publisher" type="robot_state_publisher" name="state_publisher">
       <param name="tf_prefix" type="string" value="/$(arg ns)"/>
       <param name="publish_frequency" type="double" value="20.0"/>
     </node>
 
   </group>
 
-</launch>
\ No newline at end of file
+</launch>