Declare full pnpm version

The pnpm installer will take less information, but corepack will not and
that seems to be what netlify uses. We'll have keep track of this number
and increment it with new releases.

package.json

@@ -28,5 +28,5 @@
   "devDependencies": {
     "husky": "^9.0.11"
   },
-  "packageManager": "pnpm@9"
+  "packageManager": "pnpm@9.4.0"
 }