chore(package.json): add concurrency option for dev script (#992)

close #990

# Overview

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## PR Checklist

- [x] I did below actions if need

1. I read the [Contributing
Guide](https://github.com/toss/suspensive/blob/main/CONTRIBUTING.md)
2. I added documents and tests.

package.json

@@ -32,7 +32,7 @@
     "ci:test:watch": "turbo run test:watch --parallel",
     "ci:type": "turbo run ci:type",
     "clean": "turbo run clean",
-    "dev": "turbo run dev",
+    "dev": "turbo run dev --concurrency 20",
     "format": "prettier --write \"**/*.{ts,tsx,md}\"",
     "graph": "rimraf ./graph && mkdir graph && turbo run build --graph=graph/index.html",
     "packlint": "packlint sort -R",