Add bullseye base

[zmughal]

This is the current Debian stable: https://www.debian.org/releases/bullseye/.

It is supported by the upstream container: Perl/docker-perl#107.

[oalders]

Either we would add it here https://github.com/Perl/docker-perl-tester/blob/main/.github/workflows/publish-to-docker.yml or add a new workflow. Not sure if we'd hit any rate limiting pushing all of those images to Docker Hub at once.

[oalders]

@zmughal is this still something you want added or is this obviated by having bookworm available?