fix(design-tokens): replace deprecated Sass slash division with math.div (#1127)

* fix(design-tokens): replace deprecated sass `/` division with math.div()

* chore: remove unused yarn.lock

* chore: update package-lock.json matchbox version

Author: danielfsousa

.changeset/fix-sass-slash-div.md

@@ -0,0 +1,5 @@
+---
+"@sparkpost/design-tokens": patch
+---
+
+Replace deprecated `/` division with `math.div()` in generated SCSS `rem()` and `em()` functions to fix Dart Sass 2.0 deprecation warnings

package-lock.json

@@ -20,18 +20,19 @@ const utils = (rootFontSize) => {
   const unitless = rootFontSize.value.replace('px', '');
 
   return `
+    @use "sass:math";
     @import './maps';
 
     $DEFAULT_FONT_SIZE: ${root};
     $DEFAULT_FONT_SIZE_UNITLESS: ${unitless};
 
     @function rem($n) {
-      $result: 0rem + $n / $DEFAULT_FONT_SIZE_UNITLESS;
+      $result: 0rem + math.div($n, $DEFAULT_FONT_SIZE_UNITLESS);
       @return $result;
     }
 
     @function em($n) {
-      $result: 0em + $n / $DEFAULT_FONT_SIZE_UNITLESS;
+      $result: 0em + math.div($n, $DEFAULT_FONT_SIZE_UNITLESS);
       @return $result;
     }
   `;