OSIS-5096 : fix test_learning_unit_li.py
OSIS-5096 : fix test_learning_unit_li.py

uclouvain/osis,uclouvain/osis,uclouvain/osis,uclouvain/OSIS-Louvain,uclouvain/osis,uclouvain/OSIS-Louvain,uclouvain/OSIS-Louvain