Fix AdamWeightDecay for TF 2.11 (#20735)

* Fix AdamWeightDecay for TF

* Fix AdamWeightDecay for TF

* make fixup

src/transformers/optimization_tf.py

@@ -21,6 +21,12 @@ from typing import Callable, List, Optional, Union
 import tensorflow as tf
 
 
+if hasattr(tf.keras, "optimizer") and hasattr(tf.keras.optimizer, "legacy"):
+    Adam = tf.keras.optimizer.legacy.Adam
+else:
+    Adam = tf.keras.optimizers.Adam
+
+
 class WarmUp(tf.keras.optimizers.schedules.LearningRateSchedule):
     """
     Applies a warmup schedule on a given learning rate decay schedule.
@@ -163,7 +169,7 @@ def create_optimizer(
     return optimizer, lr_schedule
 
 
-class AdamWeightDecay(tf.keras.optimizers.Adam):
+class AdamWeightDecay(Adam):
     """
     Adam enables L2 weight decay and clip_by_global_norm on gradients. Just adding the square of the weights to the
     loss function is *not* the correct way of using L2 regularization/weight decay with Adam, since that will interact