update to more closely relate to project.export_labels()

Author: jtsodapop

labelbox/schema/model_run.py

@@ -5,7 +5,6 @@
 import logging
 import requests
 import ndjson
-from labelbox.data.annotation_types.collection import LabelGenerator
 
 from labelbox.pagination import PaginatedCollection
 from labelbox.orm.query import results_query_part