proxmox/packer: Update Debian bullseye images

Related to sysadm-environment#5016 (closed)

I created 2 VMs to test the new images.
A label was added to the swap device by the post-install script:

root@gsa-temp:~# swaplabel $(awk 'NR>1{print $1}' /proc/swaps)
LABEL: swap
UUID:  ed6eeda8-8fd8-4ec3-8bed-4fe13dafe3e9