chore: remove deprecated sklearn function call

Author: xmatthias

freqtrade/freqai/base_models/FreqaiMultiOutputClassifier.py

@@ -3,7 +3,7 @@
 from sklearn.multioutput import MultiOutputClassifier, _fit_estimator
 from sklearn.utils.multiclass import check_classification_targets
 from sklearn.utils.parallel import Parallel, delayed
-from sklearn.utils.validation import has_fit_parameter
+from sklearn.utils.validation import has_fit_parameter, validate_data
 
 from freqtrade.exceptions import OperationalException
 
@@ -36,7 +36,7 @@ def fit(self, X, y, sample_weight=None, fit_params=None):
         if not hasattr(self.estimator, "fit"):
             raise ValueError("The base estimator should implement a fit method")
 
-        y = self._validate_data(X="no_validation", y=y, multi_output=True)
+        y = validate_data(self, X="no_validation", y=y, multi_output=True)
 
         if is_classifier(self):
             check_classification_targets(y)

freqtrade/freqai/base_models/FreqaiMultiOutputRegressor.py

@@ -1,6 +1,6 @@
 from sklearn.multioutput import MultiOutputRegressor, _fit_estimator
 from sklearn.utils.parallel import Parallel, delayed
-from sklearn.utils.validation import has_fit_parameter
+from sklearn.utils.validation import has_fit_parameter, validate_data
 
 
 class FreqaiMultiOutputRegressor(MultiOutputRegressor):
@@ -31,7 +31,7 @@ def fit(self, X, y, sample_weight=None, fit_params=None):
         if not hasattr(self.estimator, "fit"):
             raise ValueError("The base estimator should implement a fit method")
 
-        y = self._validate_data(X="no_validation", y=y, multi_output=True)
+        y = validate_data(self, X="no_validation", y=y, multi_output=True)
 
         if y.ndim == 1:
             raise ValueError(