APT sources: add Bullseye security
We install some packages from Bullseye. Now that there's a security repo for Bullseye, we should enable it, ideally before the Bullseye release (Aug 14).
-
devel: !626 (merged) -
stable: - wait for !625 (merged) to be merged
- backport !626 (merged): !637 (merged)
Blocked by sysadmin#17849 (closed)