Update pnpm to v8.15.9

Author: renovate[bot]

package.json

@@ -28,7 +28,7 @@
   "files": [
     "dist/**"
   ],
-  "packageManager": "[email protected].7",
+  "packageManager": "[email protected].9",
   "scripts": {
     "build": "tsup && tsup --dts-only --format esm",
     "test": "mocha \"**/*.test.ts\"",