add non-free-firmware to bookworm default components

add non-free-firmware to bookworm default components

this adds the non-free-firmware component introduced with debian
bookworm [1] to the default components for bookworm mirrors. since
this new component is a subset [2] of the previous "non-free"
component add it here too to keep the same set of packages available.

[1]: https://wiki.debian.org/Firmware#Debian_12_.28bookworm.29_and_later
[2]: https://www.debian.org/releases/bookworm/amd64/release-notes/ch-information.en.html#non-free-split

Signed-off-by: Stefan Sterz <s.sterz@proxmox.com>