use relative URL for git submodules
Currently the submodule paths are specified via "https://git.scc.kit.edu/..." URLs.
Let's use relative URLs, e.g. "../ltapi.git" instead, as per https://stackoverflow.com/questions/40841882/automatically-access-git-submodules-via-ssh-or-https
As mentioned in the comments you might have to run
git submodule sync
on your existing checkouts.
Edited by Stefan Constantin