allow public_on for sorting

Author: gr8bit

app/models/alchemy/json_api/page.rb

@@ -2,7 +2,7 @@ module Alchemy
   # With Ransack 4 we need to define the attributes
   # that are allowed to be searched.
   def Page.ransackable_attributes(_auth_object = nil)
-    super | %w[page_layout]
+    super | %w[page_layout public_version_public_on]
   end
 
   def Page.ransackable_associations(_auth_object = nil)