Remove php-cs-fixer since it is not yet compatible with symfony 6

Author: W0rma

.github/workflows/continuous-integration.yml

@@ -78,6 +78,7 @@ jobs:
         env:
           SYMFONY_REQUIRE: "${{ matrix.symfony-require }}"
         run: |
+          composer remove friendsofphp/php-cs-fixer --dev
           composer update --no-interaction --no-progress ${{ matrix.composer-flags }}
 
       - name: "Run PHPUnit"