Dart Sass 2.0.0 deprecations

[gregmartDOTin]

After upgrading Dart Sass, we're getting the following warnings:

Deprecation Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0. && "autoprefixer" plugin: Replace color-adjust to print-color-adjust. The color-adjust shorthand is currently deprecated.

It generates a ton of warnings, so let's try and update these prior to 2.0.0.