remove more unused code

Author: Peechey

src/Classes/SkillsTab.lua

@@ -7,7 +7,6 @@ local pairs = pairs
 local ipairs = ipairs
 local t_insert = table.insert
 local t_remove = table.remove
-local t_sort = table.sort
 local m_min = math.min
 local m_max = math.max