Setup dart-sass

[david-waltermire]

Committer Notes

Ensure dart-sass is setup for Hugo use.

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you squashed any non-relevant commits and commit messages? [instructions]
• Do all automated CI/CD checks pass?

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you included examples of how to use your new feature(s)?
• Have you updated all website](https://pages.nist.gov/metaschema) and readme documentation affected by the changes you made? Changes to the website can be made in the website/content directory of your branch.

[david-waltermire]

@nikitawootten-nist This should fix the Hugo issues you are having in #393.