Add missing imports

aleksis/apps/chronos/managers.py

+from datetime import datetime
 from enum import Enum
 from typing import Optional, Union
 

aleksis/apps/chronos/models.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 
 import itertools
 from collections.abc import Iterable
-from datetime import date
+from datetime import date, datetime
 from typing import Any
 
 from django.contrib.contenttypes.models import ContentType