(maint) Expands test to include macOS 12

This test excludes all versions of macOS starting from 10.15
Catalina. This commit updates the regex to exclude the newly-
release macOS 12 Monterey and any newer releases.

Author: mhashizume

acceptance/tests/resource/file/ticket_8740_should_not_enumerate_root_directory.rb

@@ -1,7 +1,8 @@
 test_name "#8740: should not enumerate root directory"
 
 confine :except, :platform => 'windows'
-confine :except, :platform => /(osx-10.1[5-9]|osx-11-)/
+confine :except, :platform => /(osx-10.1[5-9]|osx-1[1-9]-)/
+# TODO: After Puppet drops support for macOS 10.15, remove above regex and simply exclude the 'osx' platform altogether
 
 tag 'audit:high',
     'audit:refactor',   # Use block style `test_name`