Security update for python-cryptography (moderate)

This update for python-cryptography fixes the following issues:

• CVE-2018-10903: The finalize_with_tag API did not enforce a minimum tag
  length. If a user did not validate the input length prior to passing it
  to finalize_with_tag an attacker could craft an invalid payload with a
  shortened tag (e.g. 1 byte) such that they would have a 1 in 256 chance
  of passing the MAC check. GCM tag forgeries could have caused key
  leakage (bsc#1101820).

This update was imported from the SUSE:SLE-15:Update update project.