Update dependency symfony/yaml to v7

Author: renovate[bot]

composer.json

@@ -31,7 +31,7 @@
         "react/http": "^1.8",
         "reactivex/rxphp": "^2.0",
         "ringcentral/psr7": "^1.3",
-        "symfony/yaml": "^6.0",
+        "symfony/yaml": "^6.0 || ^7.0",
         "twig/twig": "^3.5",
         "wyrihaximus/async-test-utilities": "^7.0",
         "wyrihaximus/composer-update-bin-autoload-path": "^1",