[FEATURE] equal_opportunity_score positive_target should match pos_label to adhere to sklearn api

[MBrouns]

from sklearn.model_selection import cross_validate, StratifiedKFold
from sklearn.metrics import precision_score, recall_score, make_scorer
cross_validate(
    pipeline, X, y,
    scoring = {
        'eq_op_colour': equal_opportunity_score('colour', positive_target='Yes'),
        'eq_op_age': equal_opportunity_score('age', positive_target='Yes'),
        'eq_op_sex': equal_opportunity_score('sex', positive_target='Yes'),
        'precision': make_scorer(precision_score, pos_label='Yes'),
        'recall': make_scorer(recall_score, pos_label='Yes')
    },
    cv=StratifiedKFold(5)
)