Update Node.js version in GitHub Actions workflow

Author: LGYTreal

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

@@ -14,8 +14,8 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 18
-          cache: 'npm'  # ← Change from 'pnpm' to 'npm'
+          node-version: 20
+          cache: 'npm'
       - run: npm install
       - uses: FirebaseExtended/action-hosting-deploy@v0
         with: