Update ModelCheckpoint support ".h5" support (#20561)

* Update ModelCheckpoint support ".h5" support

* ModelCheckpoint support ".h5" and ".keras" both filetype

keras/src/callbacks/model_checkpoint.py

@@ -74,13 +74,14 @@ class ModelCheckpoint(Callback):
             which will be filled the value of `epoch` and keys in `logs`
             (passed in `on_epoch_end`).
             The `filepath` name needs to end with `".weights.h5"` when
-            `save_weights_only=True` or should end with `".keras"` when
-            checkpoint saving the whole model (default).
+            `save_weights_only=True` or should end with `".keras"` or `".h5"`
+            when checkpoint saving the whole model (default).
             For example:
-            if `filepath` is `"{epoch:02d}-{val_loss:.2f}.keras"`, then the
-            model checkpoints will be saved with the epoch number and the
-            validation loss in the filename. The directory of the filepath
-            should not be reused by any other callbacks to avoid conflicts.
+            if `filepath` is `"{epoch:02d}-{val_loss:.2f}.keras"` or
+            "{epoch:02d}-{val_loss:.2f}.h5"`, then the model checkpoints
+            will be saved with the epoch number and the validation loss in
+            the filename. The directory of the filepath should not be reused
+            by any other callbacks to avoid conflicts.
         monitor: The metric name to monitor. Typically the metrics are set by
             the `Model.compile` method. Note:
             * Prefix the name with `"val_"` to monitor validation metrics.
@@ -187,10 +188,12 @@ def __init__(
                     f"filepath={self.filepath}"
                 )
         else:
-            if not self.filepath.endswith(".keras"):
+            if not any(
+                self.filepath.endswith(ext) for ext in (".keras", ".h5")
+            ):
                 raise ValueError(
                     "The filepath provided must end in `.keras` "
-                    "(Keras model format). Received: "
+                    "(Keras model format) or `.h5` (HDF5 format). Received: "
                     f"filepath={self.filepath}"
                 )