Use consistent flake8 settings everywhere and fix flake8 issues

src/tests/presale/test_event.py

@@ -1,5 +1,4 @@
 import datetime
-import time
 from decimal import Decimal
 
 from django.core import mail

src/tests/presale/test_orders.py

@@ -386,7 +386,7 @@ class OrdersTest(TestCase):
         generate_invoice(self.order)
         response = self.client.get(
             '/%s/%s/order/%s/%s/pay/change' % (self.orga.slug, self.event.slug, self.order.code, self.order.secret),
-            )
+        )
         assert 'Test dummy' in response.rendered_content
         assert '+ 12.00' in response.rendered_content
         response = self.client.post(