base: whitelist Debian-Security for unattended-upgrades
Updates are coming in with that label, and should be upgraded:
e.g.
Checking: libssl1.0.2 ([<Origin component:'main' archive:'oldstable' origin:'Debian' label:'Debian-Security' site:'security.debian.org' isTrusted:True>])
Checking: libssl1.1 ([<Origin component:'main' archive:'oldstable' origin:'Debian' label:'Debian-Security' site:'security.debian.org' isTrusted:True>])
Checking: openssl ([<Origin component:'main' archive:'oldstable' origin:'Debian' label:'Debian-Security' site:'security.debian.org' isTrusted:True>])
Edited by godog