treewide: remove the-kenny from maintainers

@the-kenny did a good job in the past and is set as maintainer in many package,
however since 2017-2018 he stopped contributing. To create less confusion
in pull requests when people try to request his feedback, I removed him as
maintainer from all packages.

pkgs/development/tools/misc/dfu-programmer/default.nix

@@ -19,7 +19,6 @@ stdenv.mkDerivation rec {
     license = licenses.gpl2;
     description = "A Device Firmware Update based USB programmer for Atmel chips with a USB bootloader";
     homepage = "http://dfu-programmer.sourceforge.net/";
-    maintainers = [ maintainers.the-kenny ];
     platforms = platforms.unix;
   };
 }