Revert code change

Author: shuoweil

bigframes/ml/forecasting.py

@@ -17,7 +17,6 @@
 from __future__ import annotations
 
 from typing import List, Optional
-import warnings
 
 from google.cloud import bigquery
 
@@ -231,18 +230,6 @@ def _fit(
         """
         X, y = utils.batch_convert_to_dataframe(X, y)
 
-        # Auto-convert Date to datetime for hourly/per_minute frequency
-        if self.data_frequency in ["hourly", "per_minute"]:
-            timestamp_col = X.columns[0]
-            if "date" in X[timestamp_col].dtype.name:
-                warnings.warn(
-                    f"Converting Date column '{timestamp_col}' to datetime for "
-                    f"{self.data_frequency} frequency. This is required because "
-                    f"BigQuery ML doesn't support Date type with hourly frequency."
-                )
-                X = X.copy()
-                X[timestamp_col] = bpd.to_datetime(X[timestamp_col])
-
         if X.columns.size != 1:
             raise ValueError("Time series timestamp input X contain at least 1 column.")
         if y.columns.size != 1: