desilike+jax fix on macbook

[pmcdonal]

As I once said about cosmoprimo, putting
if jax.default_backend() != "METAL" :
in front of the jax_enable line will prevent desilike import + jax disaster on my macbook...

desilike/desilike/jax.py

Line 13 in 74a0c43

from jax.config import config; config.update('jax_enable_x64', True)