fix: add missing huawei_big_picture key (#12)

Author: netodomenico

src/OneSignalClient.php

@@ -185,6 +185,7 @@ public function postNotification($data = [], $app_id = '')
             "filters" => false,
             "firefox_icon" => false,
             "headings" => false,
+            "huawei_big_picture" => false,
             "include_amazon_reg_ids" => false,
             "include_android_reg_ids" => false,
             "include_chrome_reg_ids" => false,