gnome3.libmediaart: add updateScript

pkgs/desktops/gnome-3/misc/libmediaart/default.nix

···
 { stdenv, fetchurl, pkgconfig, glib, gdk_pixbuf, gobjectIntrospection, gnome3 }:
 
 let
-  majorVersion = "1.9";
+  pname = "libmediaart";
+  version = "1.9.4";
 in
 stdenv.mkDerivation rec {
-  name = "libmediaart-${majorVersion}.4";
+  name = "${pname}-${version}";
 
   src = fetchurl {
-    url = "mirror://gnome/sources/libmediaart/${majorVersion}/${name}.tar.xz";
+    url = "mirror://gnome/sources/${pname}/${gnome3.versionBranch version}/${name}.tar.xz";
     sha256 = "a57be017257e4815389afe4f58fdacb6a50e74fd185452b23a652ee56b04813d";
   };
 
   nativeBuildInputs = [ pkgconfig gobjectIntrospection ];
   buildInputs = [ glib gdk_pixbuf ];
+
+  passthru = {
+    updateScript = gnome3.updateScript {
+      packageName = pname;
+      attrPath = "gnome3.${pname}";
+      versionPolicy = "none";
+    };
+  };
 
   meta = with stdenv.lib; {
     description = "Library tasked with managing, extracting and handling media art caches";