fixing crypto test get_rand_digit_str
fixing crypto test get_rand_digit_str

Fixes #3303

privacyidea/privacyidea,privacyidea/privacyidea,privacyidea/privacyidea,privacyidea/privacyidea,privacyidea/privacyidea,privacyidea/privacyidea