Update dependency postcss-scss to v3 (#431)

Co-authored-by: Renovate Bot <[email protected]>

Author: renovate[bot]

package.json

@@ -32,7 +32,7 @@
     "eslint-plugin-import": "^2.17.1",
     "eslint-plugin-prettier": "^3.0.0",
     "postcss": "^8.0.0",
-    "postcss-scss": "^2.0.0",
+    "postcss-scss": "^3.0.0",
     "prettier": "~2.1.0",
     "sugarss": "^2.0.0"
   },