golden-cheetah-bin: mark insecure due to CVE-2023-4863

pkgs/applications/misc/golden-cheetah-bin/default.nix

···
     maintainers = with lib.maintainers; [ gador adamcstephens ];
     license = lib.licenses.gpl2Plus;
     sourceProvenance = with lib.sourceTypes; [ binaryNativeCode ];
+    knownVulnerabilities = [ "Vendors libwebp vulnerable to CVE-2023-4863" ];
   };
 }