madcowdzz said almost 4 years ago on GitHub Actions :
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/