Use title_translations in migrate for Mongoid 8 pluck

lib/curation/migrate.rb

@@ -9,7 +9,7 @@ module Curation
       setting = CurationSetting.first || CurationSetting.create
 
       if !setting.migrate_flag.include?("v1")
-        CurationPost.all.pluck(:id, :title).each do |id, title_translations|
+        CurationPost.all.pluck(:id, :title_translations).each do |id, title_translations|
           if title_translations.nil?
             next
           end