borgmatic 1.5.23

• #394: Compact repository segments and free space with new "borgmatic compact" action. Borg 1.2+
  only. Also run "compact" by default when no actions are specified, as "prune" in Borg 1.2 no
  longer frees up space unless "compact" is run.
• #394: When using the "atime", "bsd_flags", "numeric_owner", or "remote_rate_limit" options,
  tailor the flags passed to Borg depending on the Borg version.
• #480, #482: Fix traceback when a YAML validation error occurs.