Enable and fix lint

src/wagtail_personalisation/adapters.py

@@ -3,7 +3,6 @@ from __future__ import absolute_import, unicode_literals
 from django.conf import settings
 from django.db.models import F
 from django.utils.module_loading import import_string
-from django.utils import timezone
 
 from wagtail_personalisation.models import Segment
 from wagtail_personalisation.rules import AbstractBaseRule