message: ADD: Gazebo Transmissions for Fingers
diff: <xacro:gazebo-joint joint="${arm_id}_joint6" transmission="hardware_interface/EffortJointInterface" />
  <xacro:gazebo-joint joint="${arm_id}_joint7" transmission="hardware_interface/EffortJointInterface" />
  + <xacro:gazebo-joint joint="${arm_id}_finger_joint1" transmission="hardware_interface/EffortJointInterface" />
  + <xacro:gazebo-joint joint="${arm_id}_finger_joint2" transmission="hardware_interface/EffortJointInterface" />
  +
  <xacro:transmission-franka-state arm_id="${arm_id}" />
  <xacro:transmission-franka-model arm_id="${arm_id}"
  root="${arm_id}_joint1"
  