Update slip mejai

POST /order/2/slip/ HTTP/1.1
Host: 127.0.0.1:8000
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW
Cache-Control: no-cache
Postman-Token: 7b534e29-96dd-46e1-a2e7-18868ee631fa

------WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="slip"; filename="Screen Shot 2561-04-06 at 23.29.21.png"
Content-Type: image/png


------WebKitFormBoundary7MA4YWxkTrZu0gW--