Fix import

Author: Tschuppi81

src/onegov/event/models/occurrence.py

@@ -5,7 +5,6 @@
 from onegov.core.orm import Base
 from onegov.core.orm.mixins import TimestampMixin
 from onegov.core.orm.types import UUID
-from onegov.event.models import Event
 from onegov.event.models.mixins import OccurrenceMixin
 from onegov.gis import Coordinates
 from pytz import UTC
@@ -20,6 +19,7 @@
 from typing import TYPE_CHECKING
 if TYPE_CHECKING:
     import uuid
+    from onegov.event.models import Event
     from sqlalchemy.sql import ClauseElement