gnome: rename from gnome3

Since GNOME version is now 40, it no longer makes sense to use the old attribute name.

pkgs/development/libraries/libxmlxx/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchurl, pkg-config, libxml2, glibmm, perl, gnome3 }:
+{ lib, stdenv, fetchurl, pkg-config, libxml2, glibmm, perl, gnome }:
 
 stdenv.mkDerivation rec {
   pname = "libxml++";
@@ -16,7 +16,7 @@ stdenv.mkDerivation rec {
   propagatedBuildInputs = [ libxml2 glibmm ];
 
   passthru = {
-    updateScript = gnome3.updateScript {
+    updateScript = gnome.updateScript {
       packageName = pname;
       versionPolicy = "odd-unstable";
     };