Update to 1.47
    
    - New upstream release 1.47
      - DateTime::Duration->multiply now only allows integer multipliers (GH#73)
      - Added is_last_day_of_quarter() and is_last_day_of_year() methods (GH#72)
      - When an exception was thrown while adding a duration, the object could be
        left in a broken state with the duration partially applied; subsequent
        addition or subtraction would produce the wrong results (GH#74)
    - Add patch to support use without Sub::Util (GH#77, GH#78)