remove obsolete use of boost placeholders

these relied on an implicit include of `boost/bind.hpp` from the ros_comm
headers and ROS-O changes this include due to countless downstream warnings.

ros-o/ros_comm#3

robotiq_3f_gripper_control/src/robotiq_3f_gripper_control/robotiq_3f_gripper_ros.cpp

@@ -45,8 +45,7 @@ Robotiq3FGripperROS::Robotiq3FGripperROS(ros::NodeHandle& nh, boost::shared_ptr<
 
     //! setup dynamic reconfigure
     reconfigure_.reset(new ReconfigureServer(reconfigure_mutex_, nh_));
-    ReconfigureServer::CallbackType f = boost::bind(&Robotiq3FGripperROS::handleReconfigure, this, _1, _2);
-    reconfigure_->setCallback(f);
+    reconfigure_->setCallback([this](auto config, auto level){ handleReconfigure(config, level); });
 
     if (joint_names.size() != 4)
     {