add expire at

app/controllers/api/submissions_controller.rb

@@ -147,6 +147,7 @@ module Api
     def submissions_params
       permitted_attrs = [
         :send_email, :send_sms, :bcc_completed, :completed_redirect_url, :reply_to, :go_to_last,
+        :expire_at,
         {
           message: %i[subject body],
           submitters: [[:send_email, :send_sms, :completed_redirect_url, :uuid, :name, :email, :role,