refactor: go back to update: true

Because I now realize that's the only way we can an "mjs" and  "js" key
in there; both are needed. Update is racy, which might explain the
corrupted output.

Author: wincent

webpack.production.config.js

@@ -58,7 +58,7 @@ module.exports = BUILDS.map(({name, filename, targets, terserOptions}) => {
         fullPath: false,
         path: path.resolve(__dirname, 'dist'),
         prettyPrint: true,
-        update: false,
+        update: true,
       }),
       new MiniCssExtractPlugin({
         filename: 'styles-[contenthash].css',