[ruby/psych] Strip trailing spaces [ci skip]

https://github.com/ruby/psych/commit/e07b16ad8b

ext/psych/psych.gemspec

@@ -62,7 +62,7 @@ DESCRIPTION
     s.extensions = ["ext/psych/extconf.rb"]
     s.add_dependency 'stringio'
   end
-  
+
   s.metadata['msys2_mingw_dependencies'] = 'libyaml libyaml-devel'
 
 end