Reusable media (#3131)

Co-authored-by: Martin Gross <gross@rami.io>

src/pretix/base/models/__init__.py

@@ -40,6 +40,7 @@ from .items import (
     SubEventItem, SubEventItemVariation, itempicture_upload_to,
 )
 from .log import LogEntry
+from .media import ReusableMedium
 from .memberships import Membership, MembershipType
 from .notifications import NotificationSetting
 from .orders import (