theming: fix avatar fallback random select (#28)

Author: partizipation

apps/users/models.py

@@ -171,12 +171,12 @@ def avatar(self):
 
     @cached_property
     def avatar_fallback(self):
-        number = self.pk % 5
+        number = self.pk % 4
         return static("images/avatar-{0:02d}.svg".format(number))
 
     @cached_property
     def avatar_fallback_png(self):
-        number = self.pk % 5
+        number = self.pk % 4
         return static("images/avatar-{0:02d}.png".format(number))
 
     def get_short_name(self):