Flake8: for migrations _just_ ignore the whitespace errors

this helps catching some _real_ errors while saving us from having to format
automatically generated code

events/migrations/0015_set_event_grouping.py

@@ -23,6 +23,7 @@ def set_event_grouping(apps, schema_editor):
         grouping = issue.grouping_set.first()
         Event.objects.filter(issue=issue).update(grouping=grouping)
 
+
 class Migration(migrations.Migration):
 
     dependencies = [

projects/migrations/0011_fill_stored_event_count.py

@@ -1,5 +1,6 @@
 from django.db import migrations
 
+
 def unfill_stored_event_count(apps, schema_editor):
     Project = apps.get_model("projects", "Project")
     Project.objects.all().update(stored_event_count=0)

teams/migrations/0001_b_squashed_initial.py

@@ -18,7 +18,7 @@ class Migration(migrations.Migration):
     initial = True
 
     dependencies = [
-        migrations.swappable_dependency(settings.AUTH_USER_MODEL),  #  Defines AUTH_USER_MODEL, which we use
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),  # Defines AUTH_USER_MODEL, which we use
     ]
 
     operations = [

tox.ini

@@ -1,6 +1,8 @@
 [flake8]
 max-line-length=120
-exclude=venv,.venv,**/migrations/*,sentry/**,bugsink/event_schema.py
+exclude=venv,.venv,sentry/**,bugsink/event_schema.py
 extend-ignore=
     # E741: ambiguous variable name
     E741
+per-file-ignores =
+    **/migrations/*:E501