treewide: purge maintainers.urkud

It's sad, but he's been inactive for the last five years.
Keeping such people in meta.maintainers is counter-productive.

pkgs/development/libraries/qjson/default.nix

@@ -14,7 +14,7 @@ stdenv.mkDerivation rec {
   buildInputs = [ cmake qt4 ];
 
   meta = {
-    maintainers = [ stdenv.lib.maintainers.urkud ];
+    maintainers = [ ];
     inherit (qt4.meta) platforms;
   };
 }