fix: disable brotli compression in preview server

x-ref: https://github.com/faker-js/faker/pull/3755

Local tests suggest that `zlib.createBrotliCompress` is around 50x slower than `zlib.createGzip`. Although brotli produces 25% smaller for the test subject, such low speed is not desirable for `vitepress preview` as the command is meant for local servers.

This aligns the preview compression with vite.

src/node/serve/serve.ts

@@ -37,7 +37,7 @@ export async function serve(options: ServeOptions = {}) {
     res.end()
   }
 
-  const compress = compression({ brotli: true })
+  const compress = compression()
   const serve = sirv(config.outDir, {
     etag: true,
     maxAge: 31536000,