WIP: chore(update): upgrade base image to debian 13

[missytake]

necessary for chatmail/relay#1001

In my current setup, cmlxc init --reset led to pdns failing with:

Jun 05 11:36:24 ns-localchat [2227]: PowerDNS Recursor 5.2.9 (C) PowerDNS.COM BV
Jun 05 11:36:24 ns-localchat [2227]: Using 64-bits mode. Built using gcc 14.2.0.
Jun 05 11:36:24 ns-localchat [2227]: PowerDNS comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it according to the terms of the GPL version 2.
Jun 05 11:36:24 ns-localchat [2227]: msg="Processing main YAML settings" subsystem="config" level="0" prio="Notice" tid="0" ts="1780659384.281" path="/etc/powerdns/recursor.conf"
Jun 05 11:36:24 ns-localchat [2227]: msg="YAML config found, but error occurred processing it" error="invalid type: string \"local-address=0.0.0.0 local-port=53 forward-zones-recurse=localchat=127.0.0.1:5353 allow-from=0.0.0.0/0 dont-query= dnssec=off\", expected struct Recursorsettings" subsystem="config" level="0" prio="Error" tid="0" ts="1780659384.281" configname="/etc/powerdns/recursor.conf"
Jun 05 11:36:24 ns-localchat [2227]: msg="Trying to read YAML from .yml or .conf failed, failing back to old-style config read" subsystem="config" level="0" prio="Warning" tid="0" ts="1780659384.281" configname="/etc/powerdns/recursor.conf"
Jun 05 11:36:24 ns-localchat [2227]: msg="Old-style settings syntax not enabled by default anymore. Use YAML or enable with --enable-old-settings on the command line" subsystem="config" level="0" prio="Error" tid="0" ts="1780659384.281" configname="/etc/powerdns/recursor.conf"

[missytake]

CI uses the cached debian 12 images, how can we empty that cache?