Allow country specific tax rules (#1714)

src/pretix/base/migrations/0156_cartposition_override_tax_rate.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.0.6 on 2020-06-28 19:08
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0155_quota_release_after_exit'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='cartposition',
+            name='override_tax_rate',
+            field=models.DecimalField(decimal_places=2, max_digits=10, null=True),
+        ),
+    ]