Fix postcss dependency resolution warnings

After running `yarn install`, the output includes these warnings:

```
➤ YN0002: │ stylelint-config-gds@npm:0.2.0 [cbec9] doesn't provide postcss (p4d8da), requested by stylelint-config-standard-scss
➤ YN0002: │ stylelint-config-recommended-scss@npm:5.0.2 [9cbe8] doesn't provide postcss (pefaf8), requested by postcss-scss
```

This fixes the above warnings as recommended in this github issues
thread - stylelint-scss/stylelint-config-recommended-scss#89 (comment)

.yarnrc.yml

@@ -1,2 +1,12 @@
 yarnPath: .yarn/releases/yarn-3.5.0.cjs
 nodeLinker: node-modules
+packageExtensions:
+  stylelint-config-recommended-scss@*:
+    peerDependencies:
+      postcss: '8'
+  stylelint-config-standard-scss@*:
+    peerDependencies:
+      postcss: '8'
+  stylelint-config-gds@*:
+    peerDependencies:
+      postcss: '8'