modifying thancred to match updated flake config

flake.nix

@@ -178,7 +178,7 @@
         {
           home-manager.useGlobalPkgs = true;
           home-manager.useUserPackages = true;
-          home-manager.extraSpecialArgs = extraSpecialArgs;
+          home-manager.extraSpecialArgs = extraSpecialArgs // { isNixOS = true; role = "server"; };
           home-manager.backupFileExtension = "bak";
           home-manager.users.${userName}.imports = [
             ./home