Add composer.json existence check for extra hardening

Co-authored-by: swissspidy <841956+swissspidy@users.noreply.github.com>

Author: Copilot

.github/workflows/copilot-setup-steps.yml

@@ -19,7 +19,14 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v5
 
+      - name: Check existence of composer.json file
+        id: check_composer_file
+        uses: andstor/file-existence-action@v3
+        with:
+          files: "composer.json"
+
       - name: Set up PHP environment
+        if: steps.check_composer_file.outputs.files_exists == 'true'
         uses: shivammathur/setup-php@v2
         with:
           php-version: 'latest'
@@ -30,6 +37,7 @@ jobs:
           COMPOSER_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Install Composer dependencies & cache dependencies
+        if: steps.check_composer_file.outputs.files_exists == 'true'
         uses: ramsey/composer-install@v3
         env:
           COMPOSER_ROOT_VERSION: dev-${{ github.event.repository.default_branch }}