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`.

PiperOrigin-RevId: 559441134
Change-Id: Ic7a43f9187af53808711a1d4e02c6c49860663bf

ferminet/utils/statistics.py

@@ -19,7 +19,7 @@
 from jax import numpy as jnp
 import numpy as np
 
-T = TypeVar('T', float, np.ndarray, jnp.array)
+T = TypeVar('T', float, np.ndarray, jnp.ndarray)
 
 
 @attr.s(auto_attribs=True)