Update heroku.gemfile ruby version
Update heroku.gemfile ruby version

jayroh/thredded,jvoss/thredded,jvoss/thredded,jvoss/thredded,thredded/thredded,jayroh/thredded,thredded/thredded,jvoss/thredded,thredded/thredded,jayroh/thredded,jayroh/thredded,thredded/thredded