Convert end_date in conferences to timestamp with tz

db/migrate/20190505111757_convert_conferences_end_date_to_timestamp_with_tz.rb

@@ -0,0 +1,7 @@
+class ConvertConferencesEndDateToTimestampWithTz < ActiveRecord::Migration[5.2]
+  def up
+    transaction do
+      execute "ALTER TABLE conferences ALTER end_date TYPE timestamptz USING end_date AT TIME ZONE 'UTC';"
+    end
+  end
+end