community/py3-cryptography: remove dependency on py3-asn1rcypto

From the changelog for version 2.8 from 2019:

* ``cryptography`` no longer depends on ``asn1crypto``.

https://github.com/pyca/cryptography/blob/84eca53979d9d73dd315019a1e7c3bfc052e6865/CHANGELOG.rst#28---2019-10-16