add 3.0-gui

add 2.7-gui0

update ruby 2.6.6

Update Ruby version

2.6.0 has a known byte corruption issue over large network requests

Update Ruby version

2.6.0 has a known byte corruption issue over large network requests

Merge remote-tracking branch 'docker-library/master'

add 2.5-gui

install chrome and chromedriver for ruby 2.4-gui

add 2.4-gui

less layers for 2.3-gui