fix: move ddclient overlay to it's module

flake/config.nix

@@ -15,7 +15,6 @@
 
       # TODO: Move these to custom modules
       overlays = [
-        (import ./overlays/ddclient.nix)
         (import ./overlays/firefox-addons {
           inherit (inputs.nixpkgs) lib;
           inherit inputs;

modules/nixos/services/ddclient.nix

@@ -1,6 +1,6 @@
 {
-  lib,
   config,
+  lib,
   ...
 }: let
   cfg = config.marleyos.services.ddclient;
@@ -8,6 +8,8 @@ in {
   options.marleyos.services.ddclient.enable = lib.mkEnableOption "ddclient";
 
   config = lib.mkIf cfg.enable {
+    nixpkgs.overlays = [(import ../../../overlays/ddclient.nix)];
+
     age.secrets.ddclient.file = ../../../secrets/ddclient.conf.age;
 
     services.ddclient = {