[Test] Add Amazon Linux 2023 to spec tests.

Author: gmarciani

cookbooks/aws-parallelcluster-shared/spec/spec_helper.rb

@@ -40,6 +40,7 @@ def for_oses(os_list)
 def for_all_oses
   [
     %w(amazon 2),
+    %w(amazon 2023),
     %w(ubuntu 20.04),
     %w(ubuntu 22.04),
     %w(redhat 8),