Code changes to get ready for an incoming Keras optimizer migration.

DP optimizer only supports legacy optimizer.

PiperOrigin-RevId: 474137890

Author: chenmoneygithub

tensorflow_privacy/privacy/optimizers/dp_optimizer_keras_vectorized.py

@@ -252,8 +252,8 @@ def apply_gradients(self, *args, **kwargs):
 
 
 VectorizedDPKerasAdagradOptimizer = make_vectorized_keras_optimizer_class(
-    tf.keras.optimizers.Adagrad)
+    tf.keras.optimizers.legacy.Adagrad)
 VectorizedDPKerasAdamOptimizer = make_vectorized_keras_optimizer_class(
-    tf.keras.optimizers.Adam)
+    tf.keras.optimizers.legacy.Adam)
 VectorizedDPKerasSGDOptimizer = make_vectorized_keras_optimizer_class(
-    tf.keras.optimizers.SGD)
+    tf.keras.optimizers.legacy.SGD)