Improve / simplify logic for file attachments against test result object

InvenTree/stock/migrations/0042_auto_20200523_0121.py

@@ -0,0 +1,19 @@
+# Generated by Django 3.0.5 on 2020-05-23 01:21
+
+from django.db import migrations, models
+import stock.models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('stock', '0041_stockitemtestresult_notes'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='stockitemtestresult',
+            name='attachment',
+            field=models.FileField(blank=True, help_text='Test result attachment', null=True, upload_to=stock.models.rename_stock_item_test_result_attachment, verbose_name='Attachment'),
+        ),
+    ]