By: David Nies <david.nies@posteo.de>
Change Python version to 3.13 for the `gi` test Prior to this change, we used Python 3.14. This caused the whole pytho distribution to be rebuilt, as well as the `graph-tool` dependency. This takes very long, consumes many CPUs and RAM and ultimately makes the CI fail. This change uses python 3.13 which is cached.