treewide: Add passthru.updateScript to gnome pkgs

`updateScript` lets us update packages automatically.
For packages that are hosted on the gnome mirror it's very easy to add
that. Inspired by https://github.com/NixOS/nixpkgs/issues/36150

pkgs/development/libraries/gcab/default.nix

@@ -1,15 +1,15 @@
 { stdenv, fetchurl, gettext, gobject-introspection, pkgconfig
-, meson, ninja, glibcLocales, git, vala, glib, zlib
+, meson, ninja, glibcLocales, git, vala, glib, zlib, gnome3
 }:
 
 stdenv.mkDerivation rec {
-  name = "gcab-${version}";
+  pname = "gcab";
   version = "1.2";
 
   LC_ALL = "en_US.UTF-8";
 
   src = fetchurl {
-    url = "mirror://gnome/sources/gcab/${version}/${name}.tar.xz";
+    url = "mirror://gnome/sources/${pname}/${stdenv.lib.versions.majorMinor version}/${pname}-${version}.tar.xz";
     sha256 = "038h5kk41si2hc9d9169rrlvp8xgsxq27kri7hv2vr39gvz9cbas";
   };
 
@@ -22,10 +22,16 @@ stdenv.mkDerivation rec {
     "-Dtests=false"
   ];
 
+  passthru = {
+    updateScript = gnome3.updateScript {
+      packageName = pname;
+      versionPolicy = "none";
+    };
+  };
+
   meta = with stdenv.lib; {
     platforms = platforms.linux;
     license = licenses.lgpl21;
     maintainers = [ maintainers.lethalman ];
   };
-
 }