fix sourceB missing Grade

aes_enem_dataset.py

@@ -411,6 +411,8 @@ class HTMLParser:
             result = []
             for single_grade in grades:
                 result.append(int(single_grade.get_text()))
+            assert len(result) == 5, "We should have 5 Grades (one per concept) only"
+            result.append(sum(result)) # Add sum as a sixt element to keep the same pattern
             return result
 
     def _get_general_comment(self, soup):