More for my own knowledge but SLURM will build on EL8 but requires the PowerTools Repo and Epel Repo.
This short script worked for me.
#!/bin/bash
yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
yum-config-manager --enable CentOS-PowerTools
yum -yq groupinstall "Development Tools"
yum -yq install bzip2-devel MariaDB-devel openssl-devel munge-devel pam-devel perl python3 readline-devel zlib-devel perl-ExtUtils-MakeMaker perl-DBI rpm-build
mkdir ~/build && cd ~/build
wget -q https://download.schedmd.com/slurm/slurm-20.11.8.tar.bz2
rpmbuild -ta slurm-20.11.8.tar.bz2