micropython: reduce source size to within Hydra limit

    owner = "micropython";

    repo = "micropython";

    rev = "v${version}";

    hash = "sha256-sfJohmsqq5FumUoVE8x3yWv12DiCJJXae62br0j+190=";

    hash = "sha256-coUFIepbCRuz+766E7VCTQLm0oWB1CTO20ATriC86dc=";

    fetchSubmodules = true;

    # remove unused libaries from rp2 port's SDK. we leave this and the other

    # ports around for users who want to override makeFlags flags to build them.

    # https://github.com/micropython/micropython/blob/a61c446c0b34e82aeb54b9770250d267656f2b7f/ports/rp2/CMakeLists.txt#L17-L22

    #

    # shrinks uncompressed NAR by ~2.4G (though it is still large). there

    # doesn't seem to be a way to avoid fetching them in the first place.

    postFetch = ''

      rm -rf $out/lib/pico-sdk/lib/{tinyusb,lwip,btstack}

    '';

  };

  nativeBuildInputs = [ pkg-config python3 ];

  buildInputs = [ libffi readline ];