The current usage of ``datetime.today()`` is at the grace of the
locale settings of the test executor and the instances spun up.
The ``cryptography.x509.CertificateBuilder`` ``not_valud_before``
and ``not_valid_after`` attributes do expect [0] a UTC datetime.
0: https://cryptography.io/en/latest/x509/reference/#cryptography.x509.CertificateBuilder