Added vel and acc scaling to GetCartesianPath.srv on Humble

I'm adding these to match a pull request on moveit/moveit2 to add velocity and acceleration control to cartesian path planning on the Humble branch.

I found this portion on the Iron branch here but couldn't find references to them in moveit/moveit2 so I just left them out if anybody's wondering.

# Maximum cartesian speed for the given link.
# If max_cartesian_speed <= 0 the trajectory is not modified.
string cartesian_speed_limited_link
float64 max_cartesian_speed # m/s

srv/GetCartesianPath.srv

@@ -43,6 +43,15 @@ bool avoid_collisions
 # Specify additional constraints to be met by the Cartesian path
 Constraints path_constraints
 
+# Scaling factors for optionally reducing the maximum joint velocities and
+# accelerations.  Allowed values are in (0,1]. The maximum joint velocity and
+# acceleration specified in the robot model are multiplied by their respective
+# factors. If a factor is outside its valid range (importantly, this
+# includes being set to 0.0), this factor is set to the default value of 1.0
+# internally (i.e., maximum joint velocity or maximum joint acceleration).
+float64 max_velocity_scaling_factor
+float64 max_acceleration_scaling_factor
+
 ---
 
 # The state at which the computed path starts