Force isort to treat typing in the py3.5 style, not py3.4

src/pretix/base/signals.py

@@ -1,8 +1,9 @@
+from typing import Any, Callable, List, Tuple
+
 import django.dispatch
 from django.apps import apps
 from django.conf import settings
 from django.dispatch.dispatcher import NO_RECEIVERS
-from typing import Any, Callable, List, Tuple
 
 from .models import Event