chore(deps): update pnpm to v9.15.0 (#915)

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

package.json

@@ -2,7 +2,7 @@
   "name": "vite-ssg-sitemap",
   "type": "module",
   "version": "0.8.1",
-  "packageManager": "pnpm@9.14.4",
+  "packageManager": "pnpm@9.15.0",
   "description": "sitemap generator working with vite-ssg",
   "license": "MIT",
   "main": "dist/index.js",