nixos/ddclient: Fix ip command with usev4 and usev6

      wantedBy = [ "multi-user.target" ];

      after = [ "network.target" ];

      restartTriggers = lib.optional (cfg.configFile != null) cfg.configFile;

      path = lib.optional (lib.hasPrefix "if," cfg.use) pkgs.iproute2;

      path = lib.optional (lib.hasPrefix "if," cfg.use || lib.hasPrefix "if," cfg.usev4 || lib.hasPrefix "if," cfg.usev6) pkgs.iproute2;

      serviceConfig = {

        DynamicUser = true;