Deprecation warning inside louis
As i think we maintain louis, it would be good to fix that
tests/scans/test_external_hdf5_writer.py::test_external_hdf5_writer
/home/ordinateur/Software/miniconda3/envs/blissenv/lib/python3.7/site-packages/louie/saferef.py:133: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated since Python 3.3,and in 3.9 it will stop working
if isinstance(function, collections.Callable):