chore(deps): update pnpm to v10.21.0

Author: renovate[bot]

package.json

@@ -71,7 +71,7 @@
     "vue": "^3.5.21",
     "vuepress": "2.0.0-rc.22"
   },
-  "packageManager": "pnpm@10.16.1",
+  "packageManager": "pnpm@10.21.0",
   "engines": {
     "node": ">=18.19.0"
   },