Host detection fails with nix

[Alt-iOS]

when using nix in macos, the host detections fails because it has appended the darwin kernel version at the end, for example

elixir -e 'IO.inspect({:os.type(),
   :erlang.system_info(:system_architecture)})'

returns {{:unix, :darwin}, ~c"aarch64-apple-darwin25.3.0"} on macos tahoe

[Alt-iOS]

I created a PR to fix it, simply changed to do matches based on String.starts_with?, instead of exact strings for darwin