Update python-scikit-sound to version 0.2.13 / rev 5 via SR 1140255
    
    https://build.opensuse.org/request/show/1140255
    by user dirkmueller + anag+factory
    - update to 0.2.13:
      * try to keep file-/dir-selection windows in the front
      * Exit gracefully if user cancels file selection
      * updated docu; renamed self.info -> self.ffmpeg_info
      * left tkinter root window visible to avoid some crashes
      * [erroneous fix]
      * moved the tkinter root to the top to be visible
      * fixed error in displayed name of out-file
    
    - Remove unneeded BuildRequires on nose.
    - skip python 36 build