Address Build Deprecation Warnings for Dashboard

[michaeljmarshall]

With the switch to sass in #34, there are many deprecation warnings when you run npm run build-standalone. We should resolve them. Here is a sample:

Deprecation Warning: Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0.

Recommendation: math.div($grid-gutter-width, 2) or calc($grid-gutter-width / 2)

More info and automated migrator: https://sass-lang.com/d/slash-div

    ╷
669 │ $card-group-margin:                 ($grid-gutter-width / 2) !default;
    │                                      ^^^^^^^^^^^^^^^^^^^^^^
    ╵
    node_modules/bootstrap/scss/_variables.scss 669:38            @import
    src/vuestic-theme/vuestic-sass/resources/resources.scss 22:9  @import
    src/sass/shared.scss 18:9                                     @import
    stdin 1:9                                                     root stylesheet

The easiest way to see these is to run the build command.