fix(steam): Add packages required for some games

modules/nixos/steam.nix

@@ -23,7 +23,7 @@ in {
       dedicatedServer.openFirewall = true;
       gamescopeSession.enable = true;
       extraPackages = with pkgs; [
-        mono gtk3 gtk3-x11 libgdiplus zlib
+        mono gtk3 gtk3-x11 libgdiplus zlib nss SDL2
       ];
     };