CLSA-2024-1711036383 shim: Fix of 4 CVEs

Make this package installable only on a system having Cloudlinux signed components: grub2 and kernel - Update to shim-15.8 and fix the following CVEs: Resolves: CVE-2023-40546 Resolves: CVE-2023-40547 Resolves: СVE-2023-40548 Resolves: СVE-2023-40549 Resolves: CVE-2023-40550 Resolves:...