Updates branch aliases

- dev-master => 2.6.x-dev
- dev-develop => 2.7.x-dev

Author: weierophinney

composer.json

@@ -19,8 +19,8 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "2.5.x-dev",
-            "dev-develop": "2.6.x-dev"
+            "dev-master": "2.6.x-dev",
+            "dev-develop": "2.7.x-dev"
         }
     },
     "autoload-dev": {