Use the Slurm from EPEL #123
Description
We originally built our own version of Slurm as the EPEL version did not support PMIX etc and was out-of-date. It seems this has now been improved and so we should consider switching to use the EPEL version.
It is still very slow to update so it will lock us onto old version (the current version is 18 months old), but that comes with the benefit of not having to manage this ourselves.