maintainers: update email address for astratagem

  };

  astratagem = {

    name = "Chris Montgomery";

    email = "chris@cdom.io";

    email = "chmont@protonmail.com";

    github = "astratagem";

    githubId = 1757914;

    keys = [ { fingerprint = "6460 4147 C434 F65E C306  A21F 135E EDD0 F719 34F3"; } ];