Log Message:
xfce4-panel: update to 4.13.5

Change log:

4.13.5
======
- Bugfixes:
  - Revert "Applications menu icon sizing fixes" (Bug #14976)
  - Make sure panel plugin icons aren't clipped (LP #1756608)
  - actions: use a different icon for hybrid sleep when possible (Bug #15204)
  - Fix compiler error -Wcast-function-type (GCC 8)
  - Fix alpha-transparent background images (Bug #14850)
  - Fix this use of "defined" may not be portable
  - Bump glib version to 2.42.0
  - tasklist: Activate parent windows (Bug #15307)
  - launcher: Fix tooltip icon size (Bug #15319)
  - Hide systray frame in default panel config
  - separator: Use symbolic icon for more clarity (Bug #15359)
- Translation updates: Albanian, Arabic, Asturian, Basque, Belarusian, Bengali,
    Bulgarian, Catalan, Chinese (China), Chinese (Hong Kong), Czech, Danish,
    Dutch (Flemish), English (Australia), English (Great Britain), Estonian,
    Finnish, Galician, German, Greek, Icelandic, Indonesian, Italian, Kazakh,
    Korean, Lithuanian, Malay, Norwegian Bokmål, Norwegian Nynorsk, Occitan,
    Panjabi, Portuguese, Portuguese (Brazilian), Romanian, Russian, Serbian,
    Slovak, Slovenian, Spanish, Swedish, Thai, Turkish, Ukrainian, Uyghur,
    Vietnamese