core: remove default value for OperationLog

core/migrations/0034_operationlog.py

@@ -1,4 +1,4 @@
-# Generated by Django 2.2.6 on 2019-11-13 21:17
+# Generated by Django 2.2.6 on 2019-11-14 15:10
 
 from django.conf import settings
 from django.db import migrations, models
@@ -33,7 +33,6 @@ class Migration(migrations.Migration):
                             ("SELLING_DELETION", "Selling deletion"),
                             ("REFILLING_DELETION", "Refilling deletion"),
                         ],
-                        default="SELLING_DELETION",
                         max_length=40,
                         verbose_name="operation type",
                     ),