Project Enhancement or Maintenance Idea

Describe the enhancement or maintenance

Sass should be added as a peer dependency so developers using Checka11y.css are aware that Checka11y.css runs better with sass installed. Sass should be set as an optional peer dependency though since developers using this package may only be planning on using the vanilla CSS files, in which case they don't need sass installed (can we add a custom message?). For v2, we should also investigate whether it's possible to warn developers using node-sass since checka11y-css@2.x won't be supported by node-sass.

Acceptance criteria

• sass as an optional peer dependency with a custom message explaining why. E.g. "Only required if you're importing the raw .scss files"
• Warn developers who are using node-sass instead of sass

Why is this enhancement or maintenance important?

Improves developer experience if developers encounter any issues when installing checka11y-css.