set the cata filter to enabled by default

diff --git a/core.lua b/core.lua
index 8bd5bd6..96df8a6 100644
--- a/core.lua
+++ b/core.lua
@@ -355,6 +355,7 @@ function addon:OnInitialize()
 					expansion0 = true,
 					expansion1 = true,
 					expansion2 = true,
+					expansion3 = true,
 				},
 				-------------------------------------------------------------------------------
 				-- Item Filters (Armor/Weapon)