ci: remove pnpm version in package.json

Author: siujamo

package.json

@@ -11,7 +11,6 @@
   "keywords": [],
   "author": "Zihlu Wang",
   "license": "MIT",
-  "packageManager": "pnpm@10.10.0",
   "devDependencies": {
     "prettier": "^3.5.3",
     "vitepress": "^1.6.3"