Cryptography 43 started to warn that in version 48 it will remove
TripleDES support. Change the code to detect missing TripleDES algorithm
and do not fail.
Related: https://pagure.io/freeipa/issue/9641
Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>