update to v4

Author: hbweb

.github/workflows/firebase-hosting-merge.yml

@@ -10,7 +10,7 @@ jobs:
   build_and_deploy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - run: npm ci && npm run build
       - uses: FirebaseExtended/action-hosting-deploy@v0
         with: