Revert "Use drf-yasg for Open API documentation"

common/djangoapps/course_modes/api/serializers.py

@@ -28,10 +28,6 @@ class CourseModeSerializer(serializers.Serializer):
     sku = serializers.CharField(required=False)
     bulk_sku = serializers.CharField(required=False)
 
-    class Meta(object):
-        # For disambiguating within the drf-yasg swagger schema
-        ref_name = 'course_modes.CourseMode'
-
     def create(self, validated_data):
         """
         This method must be implemented for use in our