Related to #168

scikit-learn's CalibratedClassifierCV should work with pairs classifier:

We should ensure that it return coherent results with our estimators (could be done in #168)

This could be finalized when CalibratedClassifierCV accept 3d arrays (see issue scikit-learn/scikit-learn#13077)

TODO:

• See comment [MRG+1] Threshold for pairs learners #168 (comment)