Remove dev-master branch alias

Next version is going to be 5.0 and the master branch doesn't contain any new updates.

Author: vinkla

composer.json

@@ -46,7 +46,6 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "4.1-dev",
             "dev-develop": "5.0-dev"
         }
     },