If any package has to be pinned then create a file with the Debian version
codename in this directory.

For example, to pin packages for Debian bullseye, a file with the following
name should be created:

- pinning-bullseye

and the contents of the above file will look like the following, if we want to
pin the package "linux-libc-dev" at version "5.19.11":

Package: linux-libc-dev:*
Pin: version 5.19.11-1~bpo11+1
Pin-Priority: 500

See https://manpages.debian.org/bookworm/apt/apt_preferences.5.en.html for
more details.
