Remove obsolete branch-alias

composer.json

@@ -4,7 +4,10 @@
     "description": "The SilverStripe framework",
     "homepage": "http://silverstripe.org",
     "license": "BSD-3-Clause",
-  "keywords": ["silverstripe", "framework"],
+    "keywords": [
+        "silverstripe",
+        "framework"
+    ],
     "authors": [
         {
             "name": "SilverStripe",
@@ -30,7 +33,6 @@
         "symfony/translation": "^2.8",
         "symfony/yaml": "~3.2",
         "vlucas/phpdotenv": "^2.4",
-
         "php": ">=5.6.0",
         "ext-intl": "*",
         "ext-mbstring": "*",
@@ -54,11 +56,7 @@
     "provide": {
         "psr/container-implementation": "1.0.0"
     },
-  "extra": {
-    "branch-alias": {
-      "dev-master": "4.0.x-dev"
-    }
-  },
+    "extra": [],
     "autoload": {
         "psr-4": {
             "SilverStripe\\Control\\": "src/Control/",