[BUG] `jax.scipy.linalg.expm` does not work

[josh146]

@qml.qjit
def f(x):
    return jax.scipy.linalg.expm(-2.0 * x)

>>> f(jnp.array([[0.1, 0.2], [5.3, 1.2]]))
[/usr/local/lib/python3.10/dist-packages/jax/_src/interpreters/batching.py](https://localhost:8080/#) in get_primitive_batcher(self, primitive, frame)
    395       return self.get_axis_primitive_batcher(primitive, frame)
    396     msg = "Batching rule for '{}' not implemented"
--> 397     raise NotImplementedError(msg.format(primitive))
    398 
    399   def get_axis_primitive_batcher(self, primitive, frame):

NotImplementedError: Batching rule for 'gather' not implemented

[josh146]

@paul0403 just checking that this should still be open?

[paul0403]

@paul0403 just checking that this should still be open?

@josh146 my plan is to have seperate issue, separate PR, separate story, separate everything, for the batching rule bug and the linking bug. They really are two independent things that expm just happens to both involve.

I will make a new issue tomorrow and reference it here. For now I think reopening this is fine: after all expm still does not work