Upgrade to Debian 11 (Bullseye)

All our servers have been successfully upgraded to [Debian 11 (Bullseye)]. This upgrade has impacted almost all our services except for the ones that already ran in their own container and were already up-to-date ( such as Gitea, Jitsi Meet and Nextcloud). Most updates are changes under the hood. However, the most striking visual change is in our webmail solution Roundcube.

If there are any issues since this updates, please let us know!