public async void changePassportValidityIfExpired()
        {
            ICollection <BusPassport> busPasses = await _repo.getValidBusPassports();

            foreach (BusPassport pass in busPasses)
            {
                if (checkIfYearPassed(pass))
                {
                    await makeInvalid(pass.BusPassportId);
                }
            }
        }