FEATURE: remove the timecop gem

We should only have one way of mocking time, misuse of timecop
was causing build stability issues

app/models/topic_converter.rb

@@ -17,7 +17,8 @@ class TopicConverter
         else
           Category.where(read_restricted: false)
             .where.not(id: SiteSetting.uncategorized_category_id)
-            .first.id
+            .order('id asc')
+            .pluck(:id).first
         end
 
       @topic.archetype = Archetype.default