ci: upgrade Node.js setup action to v6 and specify node version 24

Author: victor-teles

.github/workflows/tests.yaml

@@ -9,7 +9,9 @@ jobs:
         composer-flags: [null, --prefer-lowest]
     steps:
       - uses: actions/checkout@v2
-      - uses: actions/setup-node@v1
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 24
       - uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php-version }}