Bookworm systemd backports

systemd (253~rc2-1) experimental; urgency=medium

The Debian-specific /etc/default/locale will now be made into a symlink to the distribution-agnostic /etc/locale.conf. The content format is compatible, so at upgrade time if /etc/default/locale exists it will be copied to /etc/locale.conf, if the latter does not exist.

The Debian-specific /etc/timezone will no longer be supported by systemd-timedated, as it is no longer useful and its functionality has been subsumed into /etc/localtime, and tzdata will no longer create it.