nixos: add sgx group with gid 304

fix Unknown group 'sgx', ignoring message from udev

nixos/modules/config/users-groups.nix

@@ -558,6 +558,7 @@ in {
       input.gid = ids.gids.input;
       kvm.gid = ids.gids.kvm;
       render.gid = ids.gids.render;
+      sgx.gid = ids.gids.sgx;
       shadow.gid = ids.gids.shadow;
     };
 

nixos/modules/misc/ids.nix

@@ -639,7 +639,7 @@ in
       qemu-libvirtd = 301;
       kvm = 302; # default udev rules from systemd requires these
       render = 303; # default udev rules from systemd requires these
-      # zeronet = 304; # removed 2019-01-03
+      sgx = 304; # default udev rules from systemd requires these
       lirc = 305;
       lidarr = 306;
       slurm = 307;