gonic: don't use substituteStream --replace

  postPatch = lib.optionalString transcodingSupport ''

    substituteInPlace \

      transcode/transcode.go \

      --replace \

      --replace-fail \

        '`ffmpeg' \

        '`${lib.getBin ffmpeg}/bin/ffmpeg'

  '' + ''

    substituteInPlace \

      jukebox/jukebox.go \

      --replace \

      --replace-fail \

        '"mpv"' \

        '"${lib.getBin mpv}/bin/mpv"'

  '' + ''

    substituteInPlace server/ctrlsubsonic/testdata/test* \

      --replace \

      --replace-quiet \

        '"audio/flac"' \

        '"audio/x-flac"'

  '';