Multiprocessing (ie: n_jobs=-1) in MAPIE fails when using python 3.13 and 3.12 (maybe it was failing silently for older versions).

This is the case at least when using MapieClassifier, and also most probably using MapieRegressor, TimeSeriesRegressor, and MapieMultiLabelClassifier.

Minimal code example:

from sklearn.datasets import make_classification
from mapie.classification import MapieClassifier

n_classes = 4
X, y = make_classification(
    n_samples=500,
    n_features=10,
    n_informative=3,
    n_classes=n_classes,
)

mapie_clf_multi = MapieClassifier(n_jobs=-1)
mapie_clf_multi.fit(X, y)
y_pred_multi, y_ps_multi = mapie_clf_multi.predict(X)

Returns ChildProcessError: [Errno 10] No child processes [..] (in the ResourceTracker module)

When running the test suite, the test_results_single_and_multi_jobs tests raise exceptions. Those exceptions are displayed but ignored, so the test suite passes, but the code would fail in a regular environnement.