Minify postcss parser (#6395)

* Update webpack to v4

* add todo

* add link

* Minify postcss parser

* update yarn.lock

* chore: update yarn.lock

scripts/build/build.js

@@ -99,7 +99,7 @@ async function run(params) {
     await execa("rm", ["-rf", ".cache"]);
   }
 
-  const bundleCache = new Cache(".cache/", "v14");
+  const bundleCache = new Cache(".cache/", "v15");
   await bundleCache.load();
 
   console.log(chalk.inverse(" Building packages "));