CI: Add Debian 13 to the FULL_OS runner list

This commit adds Debian 13 alias Trixie to the checked operating
systems. The image needs to be run with UEFI support.

Current Debian version overview:

• Debian 11 (Bullseye) -> "oldoldstable"
• Debian 12 (Bookworm) -> "oldstable"
• Debian 13 (Trixie) -> new "stable"

The CI will be run on Debian 12 and Debian 13 now.
Debian 11 is kept, but won't be used automatically.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes #17648