Fix isort issues

src/pretix/base/migrations/0108_auto_20190201_1527_squashed_0141_seat_sorting_rank.py

@@ -1,11 +1,12 @@
 # Generated by Django 3.0.4 on 2020-04-20 15:06
 
 from decimal import Decimal
+
+import django.db.models.deletion
+import jsonfallback.fields
 from django.conf import settings
 from django.core.cache import cache
 from django.db import migrations, models
-import django.db.models.deletion
-import jsonfallback.fields
 from django.db.models import Count
 
 import pretix.base.models.base