Fix GitHub Actions by using stable action tags

Replace SHA-based action references with stable version tags:
- actions/setup-node@60edb5dd... → @v4
- shivammathur/setup-php@e6f75134... → @v2

This resolves "action could not be found at URI" errors caused by
GitHub API issues when resolving specific commit SHAs.

🤖 Generated with [Qoder][https://qoder.com]

.github/workflows/phpunit.yml

@@ -40,7 +40,7 @@ jobs:
         uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
 
       - name: Setup PHP
-        uses: shivammathur/setup-php@e6f75134d35752277f093989e72e140eaa222f35 # v2.30.0
+        uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php }}
           extensions: dom, curl, libxml, mbstring, zip, pdo, mysql, pdo_mysql, bcmath, soap, intl, gd, exif, iconv