update the desktop restic

modules/restic/default.nix

@@ -1,13 +1,20 @@
-{ username, ... }:
+{ self, pkgs, username, ... }:
 {
+  environment.systemPackages = with pkgs; [
+    restic
+  ];
+
   services.restic.backups.${username} = {
     user = username;
     repository = "rest:http://10.7.89.30:8000";
-    timerConfig.OnCalendar = "hourly";
+    timerConfig = {
+      OnCalendar = "hourly";
+      RandomizedDelaySec = "15min";
+    };
     passwordFile = "/home/${username}/.nixos/secrets/passwords/restic.key";
     paths = [ "/home/${username}/" ];
     extraBackupArgs = [
-      "--exclude-file=/home/${username}/.nixos/modules/restic/excludes.txt"
+      "--exclude-file=${self}/modules/restic/excludes.txt"
     ];
     pruneOpts = [
       "--keep-hourly 24"