Added drop_pending_updates to setWebhook

Author: TiiFuchs

src/Telegram.php

@@ -1029,6 +1029,7 @@ public function setWebhook(string $url, array $data = []): ServerResponse
             'certificate',
             'max_connections',
             'allowed_updates',
+            'drop_pending_updates'
         ]));
         $data['url'] = $url;