Card.update_ust() got replaced by the file operation ust_update().
In addition to Change-Id I7a6a77b872a6f5d8c478ca75dcff8ea067b8203e
Fixes: f8d2e2ba08 ("split pySim/legacy/{cards,utils} from pySim/{cards,utils}")
Change-Id: Ie6405cae37493a2101e5089a8d11766fbfed4518