Merge pull request #1

* Added name for posted file

Author: axl1232

src/Webhook.php

@@ -38,7 +38,7 @@ public function send(Message $message): int
 
                 $options[CURLOPT_HTTPHEADER] = ['Content-type: multipart/form-data'];
                 $options[CURLOPT_POSTFIELDS] = [
-                    'file' => new CURLFile($file),
+                    'file' => new CURLFile($file, '', basename($file)),
                     'payload_json' => json_encode($data, JSON_THROW_ON_ERROR),
                 ];
             } else {