Warning

Please, don't merge without scheduling downtime for Weblate!
Merge of this code must be followed by the Weblate upgrade process outlined in sysadmin#17782 (closed)

Checklist

Upgrade Weblate to 4.9.1-1
Determine value of SECURE_HSTS_PRELOAD: default changed from False to ENABLE_HTTPS which in our case is True.
Determine whether we want to remove any new checks and addons (see new items in CHECK_LIST and WEBLATE_ADDONS variables in settings_docker.py).
Fix weblate_permissions.py: it's not converging.
Check whether there are any changes in relation to the current translation workflow.
Fix update-staging-website.py
Come up with an upgrade plan
Fix the pipeline
Fix use of removed attributes in tailsWeblate.py.

Edited Jan 21, 2022 by Zen Fu