Add unbuffered to distributed test (#3732)

Co-authored-by: Rhett Ying <85214957+Rhett-Ying@users.noreply.github.com>

tests/scripts/task_unit_test.sh

@@ -36,6 +36,8 @@ python3 -m pip install pytest pyyaml pandas pydantic rdflib ogb || fail "pip ins
 python3 -m pytest -v --junitxml=pytest_compute.xml tests/compute || fail "compute"
 python3 -m pytest -v --junitxml=pytest_backend.xml tests/$DGLBACKEND || fail "backend-specific"
 
+
+export PYTHONUNBUFFERED=1
 export OMP_NUM_THREADS=1
 export DMLC_LOG_DEBUG=1
 if [ $2 != "gpu" ]; then