Enable debian-archive-keyring in package source builder

We have a feature in our CI setup, wherein we can inject certain extra apt repositories to the build environment

In our case, we usually enable the debian repositories for certain use cases. But we also need the archive keyring to be able to validate the authenticity of the extra repository added.

Having the debian-archive-keying package in the package source builder can be handy, with the only exception that the docker image will be slightly larger in size.

Signed-off-by: Ritesh Raj Sarraf ritesh.sarraf@collabora.com