chore: roundcube on gustave + patch stalwart

machines/akhaten/stalwart.nix

@@ -1,7 +1,17 @@
-{ config, lib, ... }:
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
 {
   services.stalwart-mail = {
     enable = true;
+    package = pkgs.stalwart-mail.overrideAttrs (
+      _: _: {
+        patches = [ ./stalwart.patch ];
+      }
+    );
     settings = {
       authentication.fallback-admin = {
         user = "admin";