[PUI] Test result fixes (#7956)

* Prevent template adjustment

* Prevent template from being edited

* Fix 'attachment' field for StockItemTestResultSerializer

- Allow 'null' value

* Bump API version

src/backend/InvenTree/InvenTree/api_version.py

@@ -1,12 +1,15 @@
 """InvenTree API version information."""
 
 # InvenTree API version
-INVENTREE_API_VERSION = 246
+INVENTREE_API_VERSION = 247
 
 """Increment this API version number whenever there is a significant change to the API that any clients need to know about."""
 
 
 INVENTREE_API_TEXT = """
+v247 - 2024-08-22 : https://github.com/inventree/InvenTree/pull/7956
+    - Adjust "attachment" field on StockItemTestResult serializer
+    - Allow null values for attachment
 
 v246 - 2024-08-21 : https://github.com/inventree/InvenTree/pull/7862
     - Adds custom status fields to various serializers

src/backend/InvenTree/stock/serializers.py

@@ -239,7 +239,10 @@ class StockItemTestResultSerializer(
     )
 
     attachment = InvenTree.serializers.InvenTreeAttachmentSerializerField(
-        required=False
+        required=False,
+        allow_null=True,
+        label=_('Attachment'),
+        help_text=_('Test result attachment'),
     )
 
     def validate(self, data):