Allow symfony/flex plugin in CI

Author: alexander-schranz

.github/workflows/test-application.yaml

@@ -51,6 +51,9 @@ jobs:
 
             - name: Install Symfony Flex
               run: composer global require --no-progress --no-scripts --no-plugins symfony/flex
+              
+            - name: Allow Symfony Flex Plugin
+              run: composer global config --no-plugins allow-plugins.symfony/flex true
 
             - name: Install dependencies with Composer
               uses: ramsey/composer-install@v1