Compatibility fix for PyCA cryptography 42.0.0
    
    Cryptography 42.0.0 introduced two new abstract properties
    `not_valid_before_utc` and `not_valid_after_utc`, which are non-naive UTC
    variants of the `not_valid_before` and `not_valid_after` properties.
    
    The old properties are deprecated. The changeset also modifies code and
    tests to use the new `_utc` variants.
    
    Fixes: https://pagure.io/freeipa/issue/9518
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>