Remove obsolete branch-alias

composer.json

@@ -2,7 +2,10 @@
     "name": "silverstripe/userforms",
     "description": "UserForms enables CMS users to create dynamic forms via a drag and drop interface and without getting involved in any PHP code",
     "type": "silverstripe-module",
-	"keywords": ["silverstripe", "userforms"],
+    "keywords": [
+        "silverstripe",
+        "userforms"
+    ],
     "license": "BSD-3-Clause",
     "authors": [
         {
@@ -36,9 +39,5 @@
         "colymba/gridfield-bulk-editing-tools": "Allows for bulk management of form submissions",
         "silverstripe/secureassets": "Enables files uploaded via userforms to be secured from public access"
     },
-	"extra": {
-		"branch-alias": {
-			"dev-master": "4.2.x-dev"
-		}
-	}
+    "extra": []
 }