devel/py-pytest-cases: Add py-pytest-cases 3.6.14

Did you ever think that most of your test functions were actually the same test
code, but with different data inputs and expected results/exceptions?

• pytest-cases leverages pytest and its great @pytest.mark.parametrize decorator, so that you can separate your test cases from your test functions.
• In addition, pytest-cases provides several useful goodies to empower pytest. In particular it improves the fixture mechanism to support "fixture unions". This is a major change in the internal pytest engine, unlocking many possibilities such as using fixture references as parameter values in a test function. See here.

pytest-cases is fully compliant with pytest-harvest so you can easily monitor
the execution times and created artifacts. With it, it becomes very easy to
create a complete data science benchmark, for example comparing various models
on various datasets.