Tails 4.18 fixes known security vulnerabilities

This release fixes known security vulnerabilities. Upgrade as soon as possible.

Changes and updates

- Remove the "System clock synchronization" notifications when connecting to the Tor network. Removed this notification because it does not recommend a specific action for users and it was not clear.

- EliminaT Poedit

- Weblate to provide translated text for Tails and the Tails website, so Poedit is not so necessary.

- Updated the Tor browser on 10.0.16.

- Updated Thunderbird on 78.9.0-1.

- Update some Intel and Linux firmware packages. This should improve support for newer hardware (graphics, Wi-Fi and so on).

- Solved the problems

- More reliable Debian repositories. Tails now connects to APT repositories in Debian using the HTTPS address instead of their .onion address, for increased reliability with the Additional Software feature.

- An error message is displayed when the Upgrade fails to download the signing key. This was a silent error starting with 4.14.

Fix automatic update from a terminal:

torsocks curl --silent https://gitlab.tails.boum.org/tails/tails/-/raw/master/config/chroot_local-includes/usr/share/tails/certs/lets-encrypt-r3.pem \
| sudo tee --append /usr/local/etc/ssl/certs/tails.boum.org-CA.pem \
&& systemctl --user restart tails-upgrade-frontend