Change POLineItem quantity to a rounding decimal field

InvenTree/order/migrations/0017_auto_20200331_1000.py

@@ -0,0 +1,20 @@
+# Generated by Django 2.2.10 on 2020-03-31 10:00
+
+import InvenTree.fields
+import django.core.validators
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('order', '0016_purchaseorderattachment'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='purchaseorderlineitem',
+            name='quantity',
+            field=InvenTree.fields.RoundingDecimalField(decimal_places=5, default=1, help_text='Item quantity', max_digits=15, validators=[django.core.validators.MinValueValidator(0)]),
+        ),
+    ]