Add "last updated" field to supplier price break

Add model
Fixes #1697

InvenTree/company/migrations/0042_supplierpricebreak_updated.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.12 on 2022-03-14 22:19
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('company', '0041_alter_company_options'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='supplierpricebreak',
+            name='updated',
+            field=models.DateTimeField(auto_now=True, null=True, verbose_name='last updated'),
+        ),
+    ]

InvenTree/company/models.py

@@ -704,6 +704,8 @@ class SupplierPriceBreak(common.models.PriceBreak):
 
     part = models.ForeignKey(SupplierPart, on_delete=models.CASCADE, related_name='pricebreaks', verbose_name=_('Part'),)
 
+    updated = models.DateTimeField(auto_now=True, null=True, verbose_name=_('last updated'))
+
     class Meta:
         unique_together = ("part", "quantity")