Security fixes
Upgrade Tor Browser to 9.5-build2 (Closes: #17710).
Upgrade APT to 1.8.2.1 (DSA-4685).
Upgrade BIND to 1:9.11.5.P4+dfsg-5.1+deb10u1 (DSA-4689).
Upgrade WebKitGTK to 2.28.2-2~deb10u1 (DSA-4681).
Upgrade Thunderbird to 1:68.8.0-1~deb10u1 (DSA-4683).
Bugfixes
Improve Additional Software reliability (Closes: #17278): disable
periodic APT operations entirely, adjust timeouts, force data
synchronization, preserve file ownership.
Make memory erasure feature compatible with overlayfs (Closes: #15146).
Adjust various documentation for the new GitLab-based hosting.
Minor improvements and updates
Fix title of unlock-veracrypt-volume error dialog in case of incorrect
password (Closes: #17668).
Clean up confusing torrc (Closes: #17706).
Build system
IUK creation: don't use extreme compression options for the outer
SquashFS container refs.
IUK creation: add support for building several IUKs in parallel locally
(Closes: #17657).
IUK verification: add support for fetching IUKs built in parallel on
Jenkins (Closes: #17658).
Release process: generate UDFs on the alpha channel for previous
non-final releases (Closes: #17614).
Remove aufs-based IUK generation code and doc (Closes: #17489).
Test suite
Adjust for augmented timeouts in Additional Software.
Adjust locale lookup to check several directories.
Speed up 'I fill a ... MiB file' step by 1000%.
Keep latest test suite screenshot (Closes: #17621).
Fix test suite breaking when the user connects to the VM via virt-viewer
(Closes: #17623).
Adjust reference images and titles following the migration to GitLab
(Closes: #17718, 17719).