Add systemd-pam to bodhi multilib whitelist

Move it to here instead of having systemd-devel fake require
systemd-pam.

This should help with flatpak runtime packaging so that we can avoid
having to ship systemd-pam in the flatpak container.

roles/bodhi2/backend/templates/pungi.rpm.conf.j2

@@ -188,6 +188,7 @@ multilib_whitelist = {
         'syslinux-extlinux-nonlinux',
         'syslinux-nonlinux',
         'syslinux-tftpboot',
+        'systemd-pam',
         'valgrind',
         'vkBasalt',
         'wine',