Remove obsolete branch-alias

composer.json

@@ -4,7 +4,11 @@
     "description": "Reports module for SilverStripe CMS",
     "homepage": "http://silverstripe.org",
     "license": "BSD-3-Clause",
-  "keywords": ["silverstripe", "cms", "reports"],
+    "keywords": [
+        "silverstripe",
+        "cms",
+        "reports"
+    ],
     "authors": [
         {
             "name": "SilverStripe",
@@ -25,11 +29,7 @@
     "require-dev": {
         "phpunit/phpunit": "^5.7"
     },
-  "extra": {
-    "branch-alias": {
-      "dev-master": "4.0.x-dev"
-    }
-  },
+    "extra": [],
     "autoload": {
         "psr-4": {
             "SilverStripe\\Reports\\": "code/",