tinc module: use enum

Changed files
+1 -1
nixos
modules
services
networking
+1 -1
nixos/modules/services/networking/tinc.nix
···
interfaceType = mkOption {
default = "tun";
-
type = types.addCheck types.str (n: n == "tun" || n == "tap");
+
type = types.enum [ "tun" "tap" ];
description = ''
The type of virtual interface used for the network connection
'';