msitools: remove myself from maintainers

I haven't used it for a very long time,
and there's too much other things going on.

pkgs/development/tools/misc/msitools/default.nix

···
     description = "Set of programs to inspect and build Windows Installer (.MSI) files";
     homepage = https://wiki.gnome.org/msitools;
     license = [licenses.gpl2 licenses.lgpl21];
-    maintainers = [maintainers.vcunat];
     platforms = platforms.unix;
   };
 }