chore: don't throw error if build dir already exists

Author: TkDodo

packages/react-query/package.json

@@ -28,7 +28,7 @@
     "test:types": "tsc",
     "test:lib": "vitest run --coverage",
     "test:lib:dev": "pnpm run test:lib --watch",
-    "build": "mkdir ./build && cp -R ../codemods/src ./build/codemods",
+    "build": "mkdir -p ./build && cp -R ../codemods/src ./build/codemods",
     "build:types": "tsc --build"
   },
   "files": [