Allow v3 contracts where possible

Author: derrabus

composer.json

@@ -19,7 +19,7 @@
         "php": ">=7.1.3 EVEN ON LATEST SYMFONY VERSIONS TO ALLOW USING",
         "php": "THIS BRIDGE WHEN TESTING LOWEST SYMFONY VERSIONS.",
         "php": ">=7.1.3",
-        "symfony/deprecation-contracts": "^2.1"
+        "symfony/deprecation-contracts": "^2.1|^3"
     },
     "require-dev": {
         "symfony/error-handler": "^4.4|^5.0|^6.0"