Build and test on RHEL 8
Build and test on RHEL 8

This avoids el7 in the package name which is being flagged by
vulnerability scanners and calling issues for fedramp customers.

Signed-off-by: Tim Smith <764ef62106582a09ed09dfa0b6bff7c05fd7d1e4@chef.io>

chef/chef-server,chef/chef-server,chef/chef-server,chef/chef-server,chef/chef-server,chef/chef-server