Pin Symfony versions using Flex

Author: ruudk

.github/workflows/test.yaml

@@ -31,18 +31,17 @@ jobs:
                   coverage: ${{ matrix.coverage }}
                   ini-values: "memory_limit=-1"
                   php-version: ${{ matrix.php-version }}
-                  tools: composer
+                  tools: composer,flex
 
             - name: Validate composer.json
               run: composer validate --no-check-lock
 
-            - name: Configure Symfony version
-              run: composer require --no-update symfony/framework-bundle "^${{ matrix.symfony-version }}"
-
             - name: Install Composer dependencies
               uses: ramsey/composer-install@v1
               with:
                   composer-options: "--prefer-dist"
+              env:
+                  SYMFONY_REQUIRE: "${{ matrix.symfony-version }}.*"
 
             - name: Setup problem matchers for PHP
               run: echo "::add-matcher::${{ runner.tool_cache }}/php.json"