[ruby/reline] Use vterm 0.0.5 or newer on Unix like OSes because suppresses SEGV

https://github.com/ruby/reline/commit/7562cf3b5f

lib/reline/reline.gemspec

@@ -23,5 +23,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'bundler'
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'test-unit'
+  is_unix = RUBY_PLATFORM =~ /(aix|darwin|linux|(net|free|open)bsd|cygwin|solaris|irix|hpux)/i
+  spec.add_development_dependency 'vterm', '>= 0.0.5' if is_unix
   spec.add_development_dependency 'yamatanooroti', '>= 0.0.6'
 end