[LSC] change uses of jax.random.KeyArray and jax.random.PRNGKeyArray …

…to jax.Array

This change replaces uses of jax.random.KeyArray and jax.random.PRNGKeyArray in the context of type annotations with jax.Array, which is the correct annotation for JAX PRNG keys moving forward.

The purpose of this change is to remove references to KeyArray and PRNGKeyArray, which are deprecated (jax-ml/jax#17594) and will soon be removed from JAX. The design and thought process behind this is described in https://jax.readthedocs.io/en/latest/jep/9263-typed-keys.html.

Note that KeyArray and PRNGKeyArray have always been aliased to Any, so the new type annotation is far more specific than the old one.

PiperOrigin-RevId: 574006700

learned_optimization/optimizers/optax_opts.py

@@ -384,11 +384,13 @@ def __init__(self,
 
   # SM3 doesn't support scalars, so we have to reshape the params and grads.
 
-  def init(self,
-           params: Any,
-           model_state: Optional[Any] = None,
-           num_steps: Optional[int] = None,
-           key: chex.PRNGKey = None) -> SM3OptState:
+  def init(
+      self,
+      params: Any,
+      model_state: Optional[Any] = None,
+      num_steps: Optional[int] = None,
+      key: Optional[chex.PRNGKey] = None,
+  ) -> SM3OptState:
     should_reshape = jax.tree_util.tree_map(lambda x: len(x.shape) == 0, params)  # pylint: disable=g-explicit-length-test
     params = jax.tree_util.tree_map(_expand_scalar, params, should_reshape)
     out = super().init(params, model_state, num_steps, key)