Merge branch '5.1' into 5.x

* 5.1:
  Remove "version" from composer.json files, use "branch-version" instead
  [String] fix "is too large" ValueError on PHP 8

Author: nicolas-grekas

composer.json

@@ -28,5 +28,7 @@
         ]
     },
     "minimum-stability": "dev",
-    "version": "5.2.x-dev"
+    "extra": {
+        "branch-version": "5.2-dev"
+    }
 }