Copyright for bbdb source package in Lunar

This package is currently entirely a dependency package, and probably
contains nothing copyrightable.

As near as I can tell, the previous version was licensed under the GNU
public license version 2 or later. So you may also consider this
derived work to be covered under those terms.

On Debian systems, the complete text of the GNU General Public License
version 2 can be found in /usr/share/common-licenses/GPL-2 file.