Update min required parser version to v2.3

Author: paulgoetze

code_breaker.gemspec

@@ -27,7 +27,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']
 
-  spec.add_dependency 'parser',        '~> 2.2'
+  spec.add_dependency 'parser', '~> 2.3'
 
   spec.add_development_dependency 'bundler', '~> 1.10'
   spec.add_development_dependency 'rake',    '~> 10.0'