Dart Sass is deprecating division syntax outside of calc
I'm using dart-sass v1.69.5 to compile my front-end assets, including Mana and Keyrune. This is my source sass file:

```scss
@import 'mana-font/sass/mana';
@import 'keyrune/sass/keyrune';
```

And that raises the following 2 warnings:

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

Recommendation: math.div($keyrune-font-size, 1) or calc($keyrune-font-size / 1)

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

   ╷
13 │ $keyrune_font: $keyrune_font_style $keyrune_font_variant $keyrune_font_weight $keyrune_font_size/1 $keyrune_font_face !default;
   │                                                                               ^^^^^^^^^^^^^^^^^^^^
   ╵
    node_modules/keyrune/sass/_variables.scss 13:79  @import
    keyrune/sass/keyrune.scss 1:9                    @import
    app/assets/stylesheets/application.scss 5:9      root stylesheet

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

Recommendation: math.div($keyrune-font-size, $keyrune-font-size * 0 + 1) or calc($keyrune-font-size / ($keyrune-font-size * 0 + 1))

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

   ╷
12 │     width: calc(18em / #{$keyrune_font_size / ($keyrune_font_size * 0 + 1)});
   │                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   ╵
    node_modules/keyrune/sass/_helpers.scss 12:26  @import
    keyrune/sass/keyrune.scss 5:9                  @import
    app/assets/stylesheets/application.scss 5:9    root stylesheet
```