Allow usage of symfony/serializer 7.0+

Author: jdecool

composer.json

@@ -15,7 +15,7 @@
     "symfony/config": "^4.2 || ^5.0 || ^6.0",
     "symfony/dependency-injection": "^4.2 || ^5.0 || ^6.0",
     "symfony/http-kernel": "^4.3 || >=5.1.5",
-    "symfony/serializer": "^4.2 || ^5.0 || ^6.0",
+    "symfony/serializer": "^4.2 || ^5.0 || ^6.0 || ^7.0",
     "symfony/web-profiler-bundle": "^4.2 || ^5.0 || ^6.0",
     "webmozart/assert": "^1.0"
   },