`mode="reflect"` in padding is incorrect

[clemisch]

I think mode="reflect" for padding_kwargs is incorrect:

import jax.numpy as jnp
import kernex

@kernex.kmap(
    kernel_size=(3,),
    padding=("same"),
    relative=False,
    padding_kwargs=dict(mode="reflect"),
)
def f(x):
    return x

x = jnp.array([1, 2, 3, 4, 5])
y = f(x)
z = jnp.pad(x, 1, mode="reflect")

print("x: ", x)
print("y: ", y)
print("z: ", z)

gives

x:  [1 2 3 4 5]
y:  [[3 1 2]     # <-- the `3` is incorrect, should be `2`
     [1 2 3]
     [2 3 4]
     [3 4 5]
     [4 5 4]]
z:  [2 1 2 3 4 5 4]   # <-- here, the first element is `2`

The Kernex output reflects incorrectly: the first element is 3 instead of 2.