reproducible_create_meta_pkg_sets: update URL for grml dpkg.selections

With the Grml 2024.12 release, the product names change, so the URL also
changes.

In addition, the hosting situation changes and redirects need to be followed.

The new URL should start working some time on 2024-12-20.

Signed-off-by: Holger Levsen <holger@layer-acht.org>