make ResourceManager destructor virtual for derived classes

[saikishor]

After the #1354, We have the GazeboResourceManager and GZResourceManager deriving from the ResourceManager, and when compiling we have a warning from compiler about non-virtual destructor, so in this PR we change the destructor of the RM to virtual

--- stderr: gazebo_ros2_control                                      
/home/user/rolling_worspace/ros2_control_ws/src/gazebo_ros2_control/gazebo_ros2_control/src/gazebo_ros2_control_plugin.cpp:61:7: warning: base class ‘class hardware_interface::ResourceManager’ has accessible non-virtual destructor [-Wnon-virtual-dtor]
   61 | class GazeboResourceManager : public hardware_interface::ResourceManager
      |       ^~~~~~~~~~~~~~~~~~~~~
/home/user/rolling_worspace/ros2_control_ws/src/gazebo_ros2_control/gazebo_ros2_control/src/gazebo_ros2_control_plugin.cpp:61:7: warning: ‘class gazebo_ros2_control::GazeboResourceManager’ has virtual functions and accessible non-virtual destructor [-Wnon-virtual-dtor]
---

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.30%. Comparing base (465b58f) to head (0791ea0).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1607   +/-   ##
=======================================
  Coverage   87.30%   87.30%           
=======================================
  Files         108      108           
  Lines        9866     9866           
  Branches      890      890           
=======================================
  Hits         8614     8614           
  Misses        929      929           
  Partials      323      323           

Flag	Coverage Δ
unittests	87.30% <ø> (ø)

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[christophfroehlich]

Thanks, I've seen that already but forgot to report it

[fmauch]

Oh yes, absolutely!