Copyright for powerstat source package in Bookworm

Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
Upstream-Name: powerstat
Upstream-Contact: Colin Ian King 
Source: https://github.com/ColinIanKing/powerstat

Files: *
Copyright: 2011-2021, Canonical Ltd
           2021-2022, Colin Ian King
License: GPL-2+
 On Debian systems, the complete text of the GNU General Public
 License can be found in `/usr/share/common-licenses/GPL-2'.