update branch alias

Author: marc-mabe

composer.json

@@ -40,7 +40,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "4.0-dev",
+            "dev-master": "4.3-dev",
             "dev-3.x":    "3.1-dev",
             "dev-2.x":    "2.3-dev",
             "dev-1.x":    "1.3-dev"