chore(deps): update pnpm to v8.15.8

Author: renovate[bot]

package.json

@@ -18,7 +18,7 @@
     "vuepress": "2.0.0-rc.9",
     "vuepress-theme-hope": "2.0.0-rc.32"
   },
-  "packageManager": "pnpm@8.15.5",
+  "packageManager": "pnpm@8.15.8",
   "engines": {
     "node": ">=20"
   }