Dear Maintainer,

after upgrading to bookworm, sshd did not come up again. The reason is
that the config file now enforces the usage of the outdated sftp-server
subsystem, and this is not overridable.

Please consider NOT enforcing a specific sftp implementation (going with
the defaults and letting users override it in separate4 conf files), or,
if it has to be done, make it easier to override it, or possibly default
to the modern "internal-sftp" implementation which allows chroot (and thus
provides better defense-in-dpeth in most cases).

Thanks for your work!