Fix annotation download test

Author: hovnatan

tests/test_single_annotation_download.py

@@ -62,9 +62,9 @@ def test_annotation_download_upload(
 
     json1 = json.load(open(input_annotation_paths[0]))
     json2 = json.load(open(anns_json_in_folder[0]))
-    for i in json1:
+    for i in json1["instances"]:
         i.pop("classId", None)
-    for i in json2:
+    for i in json2["instances"]:
         i.pop("classId", None)
     assert json1 == json2
     if project_type == "Pixel":