ruby saas is deprecated

[ktk-sdk]

After bundle install:

    Post-install message from sass:

    Ruby Sass has reached end-of-life and should no longer be used.

    * If you use Sass as a command-line tool, we recommend using Dart Sass, the new
    primary implementation: https://sass-lang.com/install

    * If you use Sass as a plug-in for a Ruby web framework, we recommend using the
    sassc gem: https://github.com/sass/sassc-ruby#readme

    * For more details, please refer to the Sass blog:
    https://sass-lang.com/blog/posts/7828841