Debian 11: DLA-3972-1 moderate: tzdata time zone database update

- - Updated leap second list, which was set to expire by the end of
December.
- - Correction of historical data for Mexico, Mongolia and Portugal.

For Debian 11 bullseye, this problem has been fixed in version
2024b-0+deb11u1.

We recommend that you upgrade your tzdata packages.

For the detailed security status of tzdata please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/source-package/tzdata

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS