Merge branch '5.1' into 5.2

* 5.1:
  Add missing symfony/deprecation-contracts requirement

Author: jderusse

composer.json

@@ -20,6 +20,7 @@
         "ext-xml": "*",
         "symfony/config": "^4.4|^5.0",
         "symfony/dependency-injection": "^5.2",
+        "symfony/deprecation-contracts": "^2.1",
         "symfony/event-dispatcher": "^5.1",
         "symfony/http-kernel": "^5.0",
         "symfony/polyfill-php80": "^1.15",