refactor: ran pyupgrade on openedx apps (#26846)

...angoapps/coursegraph/management/commands/dump_to_neo4j.py

...ursegraph/management/commands/tests/test_dump_to_neo4j.py

...djangoapps/coursegraph/management/commands/tests/utils.py

openedx/core/djangoapps/coursegraph/tasks.py

openedx/core/djangoapps/courseware_api/serializers.py

openedx/core/djangoapps/courseware_api/tests/test_views.py

openedx/core/djangoapps/courseware_api/urls.py

openedx/core/djangoapps/courseware_api/views.py

openedx/core/djangoapps/crawlers/migrations/0001_initial.py

...djangoapps/crawlers/migrations/0002_auto_20170419_0018.py

openedx/core/djangoapps/crawlers/models.py

openedx/core/djangoapps/crawlers/tests/test_models.py