Update _get_column_info()

Series.__getitem__ treating keys as positions is deprecated.

See: https://github.com/pandas-dev/pandas/blob/2.1.x/pandas/core/series.py#L1027-L1037

Author: debnath-d

ISLP/models/columns.py

@@ -148,7 +148,7 @@ def _get_column_info(X,
             name = f'X{col}'
         else:
             name = str(col)
-        if is_categorical[i]:
+        if is_categorical.iloc[i]:
             if is_ordinal[i]:
                 Xcol = _get_column(col, X) 
                 encoder = clone(default_encoders['ordinal'])