Fix for broken migration (#6873)

* Fix for broken migration

- Ref: https://github.com/inventree/InvenTree/actions/runs/8451665220/job/23150490238

* Update migration

* Renove nullable from test_station field

* File cleanup

InvenTree/stock/migrations/0109_add_additional_test_fields.py

@@ -13,12 +13,12 @@ class Migration(migrations.Migration):
         migrations.AddField(
             model_name='stockitemtestresult',
             name='finished_datetime',
-            field=models.DateTimeField(blank=True, help_text='The timestamp of the test finish', verbose_name='Finished'),
+            field=models.DateTimeField(blank=True, help_text='The timestamp of the test finish', null=True, verbose_name='Finished'),
         ),
         migrations.AddField(
             model_name='stockitemtestresult',
             name='started_datetime',
-            field=models.DateTimeField(blank=True, help_text='The timestamp of the test start', verbose_name='Started'),
+            field=models.DateTimeField(blank=True, help_text='The timestamp of the test start', null=True, verbose_name='Started'),
         ),
         migrations.AddField(
             model_name='stockitemtestresult',