Log Message:
libxfce4ui: update to 4.13.6

Change log:

4.13.6
======
- Update active contributors
- Translation Updates:
  Albanian, Belarusian, Catalan, Danish, Dutch (Flemish), English
  (Australia), Finnish, Galician, Hebrew, Hungarian, Italian, Japanese,
  Kazakh, Malay, Portuguese, Portuguese (Brazilian), Russian, Serbian,
  Spanish, Thai, Turkish