Changing /boot mount point to /boot/firmware
When upgrading from bullseye, firmware path change from boot to /boot/firmware, this should provide a working upgrade path.
It might be rework a bit to fit well debian update/upgrade policy that I'm not really aware of (rename fstab backup or call an upgrade routine etc...).
This pr should resolve https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1055901