treewide: remove wkennington as maintainer

He prefers to contribute to his own nixpkgs fork triton.
Since he is still marked as maintainer in many packages
this leaves the wrong impression he still maintains those.

pkgs/development/libraries/libstatgrab/default.nix

@@ -16,6 +16,5 @@ stdenv.mkDerivation rec {
     description = "A library that provides cross platforms access to statistics about the running system";
     license = licenses.gpl2;
     platforms = platforms.unix;
-    maintainers = with maintainers; [ wkennington ];
   };
 }