broker: fix eval

hosts/broker/default.nix

@@ -1,4 +1,4 @@
-{ config, pkgs, ... }:
+{ config, lib, pkgs, ... }:
 
 let
   mymqttui = pkgs.writeScriptBin "mqttui" ''
@@ -132,11 +132,11 @@ in
     };
   };
 
-  environment.systemPackages = with pkgs; [
+  environment.systemPackages = [
     mymqttui
   ];
 
-  users.motdFile = ./motd;
+  users.motdFile = lib.mkForce ./motd;
 
   system.stateVersion = "22.05";
 }