Update matthiasnoback/symfony-dependency-injection-test requirement

Updates the requirements on [matthiasnoback/symfony-dependency-injection-test](https://github.com/matthiasnoback/SymfonyDependencyInjectionTest) to permit the latest version.
- [Release notes](https://github.com/matthiasnoback/SymfonyDependencyInjectionTest/releases)
- [Changelog](https://github.com/SymfonyTest/SymfonyDependencyInjectionTest/blob/master/CHANGELOG.md)
- [Commits](SymfonyTest/SymfonyDependencyInjectionTest@5.0.0...6.0.0)

---
updated-dependencies:
- dependency-name: matthiasnoback/symfony-dependency-injection-test
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

composer.json

@@ -38,7 +38,7 @@
         "sylius/mailer": "self.version"
     },
     "require-dev": {
-        "matthiasnoback/symfony-dependency-injection-test": "^5.0",
+        "matthiasnoback/symfony-dependency-injection-test": "^6.0",
         "phpspec/phpspec": "^7.0",
         "phpstan/phpstan": "1.12.5",
         "phpstan/phpstan-phpunit": "1.4.0",