chore: replace sass @import with @use to reduce console warnings (#3122)

We use sass for our `@kong/design-tokens` support.

This applies another fix for a recent sass upgrade to prevent
`@kong/design-tokens` related console warnings:

Note there are still some deprecation warnings due to our own usage of
sass, but this gets rid of the majority of noise.

Whilst we have to use sass in order to consume `@kong/design-tokens`, a
the better fix for our own code is to get rid of sass usage entirely. So
I hope/plan on doing that in a follow up PR relatively soon. (edit: I
made a follow up issue #3123)

Signed-off-by: John Cowen <[email protected]>

vite.config.production.ts

@@ -71,7 +71,7 @@ export const config: UserConfigFn = () => {
       preprocessorOptions: {
         scss: {
           additionalData: hoistUseStatements(`
-            @import "@kong/design-tokens/tokens/scss/variables";
+            @use "@kong/design-tokens/tokens/scss/variables" as *;
           `),
           api: 'modern-compiler',
         },