Allow empty datetime fields in APIToken model admin.
Review Request #12526 — Created Aug. 10, 2022 and submitted
APITokenmodel includes several datetime fields which are allowed
to be blank (such as invalidation or expiration). However, the
definitions of these fields were missing
blank=True, which meant that
the auto-generated form used in the admin site showed these fields as
required. This change fixes that.
Was able to save an APIToken with these fields as blank.