Add SubEvent.last_modified

src/pretix/base/migrations/0164_subevent_last_modified.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.0.9 on 2020-10-15 16:12
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0163_device_security_profile'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='subevent',
+            name='last_modified',
+            field=models.DateTimeField(auto_now=True, db_index=True),
+        ),
+    ]