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/libmbim/default.nix

@@ -22,6 +22,5 @@ stdenv.mkDerivation rec {
     description = "Library for talking to WWAN modems and devices which speak the Mobile Interface Broadband Model (MBIM) protocol";
     platforms = platforms.linux;
     license = licenses.gpl2;
-    maintainers = with maintainers; [ wkennington ];
   };
 }