Update branch alias for new branch structure

Author: stayallive

composer.json

@@ -64,7 +64,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-3.x": "3.x-dev",
+            "dev-master": "3.x-dev",
             "dev-2.x": "2.x-dev",
             "dev-1.x": "1.x-dev",
             "dev-0.x": "0.x-dev"