keepass-keefox: add myself as a maintainer

lib/maintainers.nix

···
   mingchuan = "Ming Chuan <[e-mail]>";
   mirdhyn = "Merlin Gaillard <[e-mail]>";
   mirrexagon = "Andrew Abbott <[e-mail]>";
+  mjanczyk = "Marcin Janczyk <[e-mail]>";
   mlieberman85 = "Michael Lieberman <[e-mail]>";
   modulistic = "Pablo Costa <[e-mail]>";
   mog = "Matthew O'Gorman <[e-mail]>";

pkgs/applications/misc/keepass-plugins/keefox/default.nix

···
       homepage    = http://keefox.org;
       platforms   = with stdenv.lib.platforms; linux;
       license     = stdenv.lib.licenses.gpl2;
+      maintainers = [ stdenv.lib.maintainers.mjanczyk ];
     };
 
     buildInputs = [ unzip ];