added clean migration steps for all price fields

InvenTree/stock/migrations/0065_auto_20210701_0509.py

@@ -0,0 +1,25 @@
+# Generated by Django 3.2.4 on 2021-07-01 05:09
+
+import InvenTree.fields
+from django.db import migrations
+import djmoney.models.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('stock', '0064_auto_20210621_1724'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='stockitem',
+            name='purchase_price',
+            field=InvenTree.fields.InvenTreeModelMoneyField(blank=True, currency_choices=[], decimal_places=4, default_currency='', help_text='Single unit purchase price at time of purchase', max_digits=19, null=True, verbose_name='Purchase Price'),
+        ),
+        migrations.AlterField(
+            model_name='stockitem',
+            name='purchase_price_currency',
+            field=djmoney.models.fields.CurrencyField(choices=[], default='', editable=False, max_length=3),
+        ),
+    ]