`readmeta` for `mlx.metallib` returns a 1-element array of MachO Handle (32-bit)

[stemann]

Calling readmeta on mlx.metallib from https://files.pythonhosted.org/packages/93/07/57feaad207d1ce0d690d255cda0c35b9246911cc24f2f3c0634000ed658f/mlx-0.20.0-cp313-cp313-macosx_13_0_arm64.whl does not return a FatMachOHandle as expected in runtests.jl#L184, but instead returns:

readmeta(open(joinpath(pwd(), "test", "macmetal", "mlx.metallib")))
1-element Vector{MachOHandle{IOStream}}:
 MachO Handle (32-bit)

I know #38 only added rudimentary support for handling metallib's - mostly just reporting this to keep track of the issue.

[giordano]

CC: @maleadt