Upgrade Slurm

[XaverStiensmeier]

When upgrading slurm we need to ensure stability for already running clusters. We therefore have decided to keep the current package and release a second package called slurm-bibigrid. We will pin the slurm version in future bibigrid releases and by that ensure cluster stability (i.e. avoid that workers are started on demand with a newer slurm version than the master).