Add unittest
Currently the unittest are just print: https://gitlab.eclipse.org/eclipse/aidge/aidge_quantization/-/blob/3ebb91c6/aidge_quantization/unit_tests/aidge_ptq.py?ref_type=heads
We should use the unittest framework, a short documentation on how to do is written in the project wiki: https://gitlab.eclipse.org/groups/eclipse/aidge/-/wikis/python%20test