Handle query for the audit logs of deleted objects

If an object is deleted, the current code cannot find the object or its related objects,
and causes an error in the Audit Log feature when we try to filter that object.
In that case, we directly use the object_id and content_type_id fields of the Audit model
to find it and skip finding the related objects.

promgen/views.py

@@ -214,7 +214,18 @@ def get_queryset(self):
 
         for key in self.FILTERS:
             if key in self.request.GET:
-                obj = self.FILTERS[key].objects.get(pk=self.request.GET[key])
+                try:
+                    obj = self.FILTERS[key].objects.get(pk=self.request.GET[key])
+                except self.FILTERS[key].DoesNotExist:
+                    # If we can't find the object (maybe because it was deleted),
+                    # we will search in the audit log by content_type and object_id
+                    # and skip finding the related objects.
+                    queryset = queryset.filter(
+                        object_id=self.request.GET[key],
+                        content_type_id=ContentType.objects.get_for_model(self.FILTERS.get(key)).id,
+                    )
+                    continue
+
                 # Get any log entries for the object itself
                 qset = Q(
                     object_id=obj.id,