CLSA-2024-1721204645 shim-signed: Fix of 4 CVEs

Make this package installable on a system having a either Centos or Cloudlinux signed 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: CVE-2023-40551...