add package discovery laravel 5.5+

Author: ricardovanlaarhoven

composer.json

@@ -38,5 +38,12 @@
     "config": {
         "sort-packages": true
     },
-    "minimum-stability": "dev"
+    "minimum-stability": "dev",
+    "extra": {
+        "laravel": {
+            "providers": [
+                "NotificationChannels\\Messagebird\\MessagebirdServiceProvider"
+            ]
+        }
+    }
 }