is_categorical deprecated (#266)

pandas-dev/pandas#33385

Author: philip-khor

category_encoders/utils.py

@@ -18,7 +18,7 @@ def convert_cols_to_list(cols):
         return list(cols)
     elif isinstance(cols, tuple):
         return list(cols)
-    elif pd.api.types.is_categorical(cols):
+    elif pd.api.types.is_categorical_dtype(cols):
         return cols.astype(object).tolist()
 
     return cols