fix: Add undocumented github.repository_visibility option

[rasa]

See https://www.google.com/search?q=github+%22repository_visibility%22

As a workaround, one can add this to your actionlint.yml file:

paths:
  # This pattern matches any YAML file under the '.github/workflows/' directory.
  .github/workflows/**/*:
    ignore:
      # Ignore undocumented option repository_visibility.
      - 'repository_visibility'

[rhysd]

I confirmed the undocumented property exists.

[rhysd]

I will fix the lint error after merging this.