Xcode 12 Beta 4 Released

@bytesguy I think you might have seen this issue from me iOS Fastlane build fails on bundle install `digest-crc` dependency on Xcode 12 beta 3 image

Where exactly should I put

run:
  name: Set Ruby Version
  command: echo 'chruby ruby-2.6' >> ~/.bash_profile

in my config.yml file?

Should it be run as a command? Or can I just add it on the top of the file?