quassel: use qt4 version of the daemon because as of now qt5 version fails to use proxies(connection refused)

nixos/modules/services/networking/quassel.nix

···
 with lib;
 
 let
-  quassel = pkgs.quasselDaemon_qt5;
+  quassel = pkgs.kde4.quasselDaemon;
   cfg = config.services.quassel;
   user = if cfg.user != null then cfg.user else "quassel";
 in