Use max_by to determine the maximum value

This gives the same result, but it's much easier to read what's going
on.

Author: ekohl

lib/rspec-puppet-facts.rb

@@ -412,7 +412,7 @@ def self.facter_version_for_puppet_version(puppet_version)
       return Facter.version
     end
 
-    applicable_versions.sort { |a, b| b.first <=> a.first }.first.last
+    applicable_versions.max_by { |p, _| p }.last
   rescue JSON::ParserError
     warning "#{json_path} contains invalid JSON, defaulting to Facter #{Facter.version}"
     Facter.version