GitLab upgrade completed. Current version is 17.11.3.
This PR simply adds a template for the slides based on the presentation at cluster22 I added to the flake a target to build the container for the CI of the slides As I am on arm right now, I will either let you build it and push it to the registry of this repository, or do it later when i'll have access to a x86 machine. I added the step to the CI