My Setup Ruby task is giving me the following error. It seems as though Github has changed their Actions a month after this video was released.
Run ruby/setup-ruby@v1.45.0
Error: Unable to process command '::add-path::/home/runner/.rubies/ruby-2.6.6/bin' successfully.
Error: The `add-path` command is disabled. Please upgrade to using Environment Files or opt into unsecure command execution by setting the `ACTIONS_ALLOW_UNSECURE_COMMANDS` environment variable to `true`. For more information see: https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/
☒ It looks like they have gone through several updates. Check out https://github.com/marketplace/actions/setup-ruby-jruby-and-truffleruby and click on the green dropdown on the top right to see the different versions. They do recommend to use ruby/setup-ruby@v1 which I guess will take in all of the updates.