[JAX] Replace uses of jnp.array in types with jnp.ndarray. (#26703)

`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`.

Co-authored-by: Peter Hawkins <phawkins@google.com>

templates/adding_a_new_model/cookiecutter-template-{{cookiecutter.modelname}}/modeling_flax_{{cookiecutter.lowercase_modelname}}.py

@@ -251,7 +251,7 @@ class Flax{{cookiecutter.camelcase_modelname}}SelfAttention(nn.Module):
         hidden_states,
         attention_mask,
         layer_head_mask,
-        key_value_states: Optional[jnp.array] = None,
+        key_value_states: Optional[jnp.ndarray] = None,
         init_cache: bool = False,
         deterministic=True,
         output_attentions: bool = False,