Release task (return to queue) with delay if specified

            :param task_id: Task id
            :param delay: Time in seconds before task will become ready again
            :return: Task instance

async def release(self, task_id, *, delay=None):
        """
            Release task (return to queue) with delay if specified

            :param task_id: Task id
            :param delay: Time in seconds before task will become ready again
            :return: Task instance
        """
        opts = {}
        if delay is not None:
            opts['delay'] = delay
        args = (task_id, opts)
        res = await self.conn.call(self.__funcs['release'], args)
        return self._create_task(res.body)