Remove unique_together requirement for purchaseorderlineitem

- Allow a single purchase order to specify duplicate lines (e.g. split shipments / order scheduling)

InvenTree/order/migrations/0063_alter_purchaseorderlineitem_unique_together.py

@@ -0,0 +1,17 @@
+# Generated by Django 3.2.10 on 2022-02-28 04:27
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('order', '0062_auto_20220228_0321'),
+    ]
+
+    operations = [
+        migrations.AlterUniqueTogether(
+            name='purchaseorderlineitem',
+            unique_together=set(),
+        ),
+    ]

InvenTree/order/models.py

@@ -839,7 +839,6 @@ class PurchaseOrderLineItem(OrderLineItem):
 
     class Meta:
         unique_together = (
-            ('order', 'part', 'quantity', 'purchase_price')
         )
 
     @staticmethod