Update pnpm to v11.21.0 (#146)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

package.json

@@ -2,7 +2,7 @@
   "name": "astro.new",
   "type": "module",
   "private": true,
-  "packageManager": "pnpm@11.20.0",
+  "packageManager": "pnpm@11.21.0",
   "engines": {
     "node": "24.19.0"
   },