Depend on the syslog gem

Since Ruby 3.4 the syslog gem changed from a default gem to a bundled
gem.

syslog is used to determine if the system is posix. On Windows it will
still fail to load the actual extension so the detection still works.

Author: ekohl

puppet.gemspec

@@ -34,6 +34,7 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency('racc', '~> 1.5')
   spec.add_runtime_dependency('scanf', '~> 1.0')
   spec.add_runtime_dependency('semantic_puppet', '~> 1.0')
+  spec.add_runtime_dependency('syslog', '>= 0.1', '< 0.3')
 
   platform = spec.platform.to_s
   if platform == 'universal-darwin'