Fix numpy iterable import in _causal_analysis.py for numpy>2.0 (py-why#945)

Signed-off-by: Ilya Matiach <ilmat@microsoft.com>
Signed-off-by: Carl Gold <carl@offerfit.ai>

Author: imatiach-msft

econml/solutions/causal_analysis/_causal_analysis.py

@@ -9,7 +9,7 @@
 import joblib
 import lightgbm as lgb
 import numpy as np
-from numpy.lib.function_base import iterable
+from numpy import iterable
 import pandas as pd
 from sklearn.base import BaseEstimator, TransformerMixin
 from sklearn.compose import ColumnTransformer