haskell-gi-gdkx11: drop obsolete override

Closes https://github.com/NixOS/nixpkgs/issues/37724.

pkgs/development/haskell-modules/configuration-common.nix

@@ -422,8 +422,9 @@ self: super: {
   # https://github.com/evanrinehart/mikmod/issues/1
   mikmod = addExtraLibrary super.mikmod pkgs.libmikmod;
 
+  # The doctest phase fails because it does not have a proper environment in
+  # which to run the commands it's ought to test.
   haskell-gi = dontCheck super.haskell-gi;
-  gi-gdkx11 = super.gi-gdkx11.override { gdk-x11 = pkgs.gtk3; };
 
   # https://github.com/basvandijk/threads/issues/10
   threads = dontCheck super.threads;