Add missing php setup step in workflow

.github/workflows/php-test-standalone-plugins.yml

@@ -58,13 +58,22 @@ jobs:
     steps:
       - uses: styfle/[email protected]
       - uses: actions/checkout@v3
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
       - name: Setup Node.js (.nvmrc)
         uses: actions/setup-node@v3
         with:
           node-version-file: '.nvmrc'
           cache: npm
       - name: npm install
         run: npm ci
+      - name: General debug information
+        run: |
+          npm --version
+          node --version
+          composer --version
+          php -v
       - name: Building standalone plugins
         run: npm run build-plugins
       - name: Running single site standalone plugin integration tests