buster-based images moved to archive.debian.net

Hi,

In order to save time in my ci setup, I install a few things using apt, rather than relying on Alien modules (in my case, Alien::ffmpeg) to download and compile software, which takes significantly longer.

On the images for the oldest perl that I support, 5.28, this has recently stopped working, as the images are based on Debian 11 'buster', which no longer lives on deb.debian.org but instead has moved to archive.debian.net.

While the fix for this is trivial (just s/deb.debian.org/archive.debian.net/ over /etc/apt/sources.list), and I can do that from my CI script, I think it would be better if the docker images were to be updated to use the new URL. This should theoretically be fairly trivially a simple rebuild with no changes to the Dockerfile as the buster images currently should already have the new URL baked in, though I haven't tested this myself.

Start by inspecting the Dockerfiles and build configuration for the Perl 5.28/Buster images, then check how /etc/apt/sources.list is populated. Rebuild the affected images and verify that apt installs work using archive.debian.net without requiring a CI-side replacement.