[JAX] Replace uses of jnp.array in types with jnp.ndarray.

`jnp.array` is a function, not a type:
https://jax.readthedocs.io/en/latest/_autosummary/jax.numpy.array.html
so it never makes sense to use `jnp.array` in a type annotation.

Presumably the intent was to write `jnp.ndarray` aka `jax.Array`. Change uses of `jnp.array` to `jnp.ndarray`.

PiperOrigin-RevId: 555454626
Change-Id: I089d1c5a0988f2b608fce41cc345c86f17b8957c

acme/agents/jax/ppo/normalization.py

@@ -132,9 +132,12 @@ def init() -> EMAMeanStdNormalizerParams:
         biased_second_moment=second_moment,
     )
 
-  def _normalize_leaf(x: jnp.array, ema_counter: jnp.int32,
-                      biased_first_moment: jnp.array,
-                      biased_second_moment: jnp.array) -> jnp.ndarray:
+  def _normalize_leaf(
+      x: jnp.ndarray,
+      ema_counter: jnp.int32,
+      biased_first_moment: jnp.ndarray,
+      biased_second_moment: jnp.ndarray,
+  ) -> jnp.ndarray:
     zero_debias = 1. / (1. - jnp.power(tau, ema_counter))
     mean = biased_first_moment * zero_debias
     second_moment = biased_second_moment * zero_debias