Remove deprecated attributes from Debates

Some fields from Debates are deprecated and we no longer need them.

db/migrate/20200831112936_remove_deprecated_fields_from_debates.rb

@@ -0,0 +1,6 @@
+class RemoveDeprecatedFieldsFromDebates < ActiveRecord::Migration[5.1]
+  def change
+    remove_column :debates, :deprecated_title, :string
+    remove_column :debates, :deprecated_description, :text
+  end
+end

db/schema.rb

@@ -480,8 +480,6 @@ ActiveRecord::Schema.define(version: 20200908084257) do
   end
 
   create_table "debates", id: :serial, force: :cascade do |t|
-    t.string "deprecated_title", limit: 80
-    t.text "deprecated_description"
     t.integer "author_id"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false