Cinder already removed support for Python 3.8, thus it no longer has
to use the wrapper function from oslo.utils but can use the md5 method
from hashlib directly.
The md5 function from oslo.utils is being deprecated by [1].
[1] https://review.opendev.org/c/openstack/oslo.utils/+/930879
Change-Id: Ief1f4951b7b3b4fb8e7ba599cd7138f62b39d46f