Allow v3 contracts where possible

Author: derrabus

composer.json

@@ -23,7 +23,7 @@
     "require-dev": {
         "symfony/http-kernel": "^4.4|^5.0|^6.0",
         "symfony/serializer": "^4.4|^5.0|^6.0",
-        "symfony/deprecation-contracts": "^2.1"
+        "symfony/deprecation-contracts": "^2.1|^3"
     },
     "autoload": {
         "psr-4": { "Symfony\\Component\\ErrorHandler\\": "" },