`Perm16::random` always returns the identity

[james-d-mitchell]

So, on my computer (Apple M4), I get PPerm16::random(i) returning the identity permutation for every input value i. Not sure if this is an ARM vs Intel issue or if something else is going on. I noticed this when creating the python bindings for HPCombi in

libsemigroups/libsemigroups_pybind11#355