Merge pull request #260821 from zzzsyyy/update/xanmod

let

  # These names are how they are designated in https://xanmod.org.

  ltsVariant = {

    version = "6.1.55";

    hash = "sha256-kmiMbzH1hyteicjk1WfCQPYhLsVAbl1t5LJ83rUNZ1k=";

    version = "6.1.57";

    hash = "sha256-ZzZj1Ij9L6WtjEJRcOdNtZ18oFRybNPV4uID6umC2Zg=";

    variant = "lts";

  };

  mainVariant = {

    version = "6.5.5";

    hash = "sha256-XjSuhZ5ooXOVllKc29Pd+PlOK6OtcgVMVFzxOx5nkIw=";

    version = "6.5.7";

    hash = "sha256-D4DMyBSaBZXHScmpkC3/fKlDylO1xVSZhar2F5bMjkY=";

    variant = "main";

  };