This was done for the python linker and numba linker.

deepcopy seems to be the recommended method for
copying a numpy Generator.

After this numpy PR:
https://github.com/numpy/numpy/pull/26293/commits/44ba7ca07984557f2006f9a6916adb8e3ecfca61
`copy` didn't seem to actually make an independent copy of
the `np.random.Generator` objects spawned by `RandomStream`.

This was causing the "test values" computed by e.g.
`RandomStream.uniform` to increment the RNG state, which
was causing tests that rely on `RandomStream` to fail.

Here is some related discussion:
https://github.com/numpy/numpy/issues/24086

I didn't see any official documentation about
a change in numpy that would make copy stop
working.