bump up teeny version to 2.6.6.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_6@67822 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
bump up teeny version to 2.6.6.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_6@67822 b2dd03c8-39d4-4d8f-98ff-823fe69b080e