networking: fix not setting hostname

Author: khaneliman

modules/nixos/system/networking/default.nix

@@ -2,6 +2,7 @@
   config,
   lib,
   pkgs,
+  hostname,
 
   ...
 }:
@@ -127,6 +128,8 @@ in
     ];
 
     networking = {
+      hostName = hostname;
+
       hosts = {
         "127.0.0.1" = cfg.hosts."127.0.0.1" or [ ];
       } // cfg.hosts;