fix: use is-sponsor-label-action v2 (v3 does not exist)

The v3 release does not exist for JasonEtco/is-sponsor-label-action.
Use v2 which is the latest stable release. The Node.js 24 compatibility
is handled by the FORCE_JAVASCRIPT_ACTIONS_TO_NODE24 environment variable.

.github/workflows/labeler.yml

@@ -53,6 +53,6 @@ jobs:
     steps:
       - name: Is Sponsor Label
         if: github.event.action == 'opened'
-        uses: JasonEtco/is-sponsor-label-action@v3
+        uses: JasonEtco/is-sponsor-label-action@v2
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}