Copyright for laby source package in Focal

Format-Specification: http://wiki.debian.org/Proposals/CopyrightFormat

Packaged-By: Mehdi Dogguy https://sgimenez.github.io/laby/
Upstream-Author: Stéphane Gimenez  (and al.)

Files: *
Copyright: © 2007-2014 The laby team
Licence: GPL-3+
  See `/usr/share/common-licenses/GPL-3'.

Files: debian/*
Copyright: © 2009-2016 Mehdi Dogguy 
License: GPL-3+