Please how may we upload a file as described below with Tesla?

For a self-signed certificate an extra parameter is needed, certificate , with the public certificate in PEM format as data.

• A curl example for a self-signed certificate:
  curl -F "url=https://<YOURDOMAIN.EXAMPLE>/<WEBHOOKLOCATION>" -F "certificate=@<YOURCERTIFICATE>.pem" https://api.telegram.org/bot<YOURTOKEN>/setWebhook

The -F means we’re using the multipart/form-data -type to supply the certificate
(Marvin's Marvellous Guide to All Things Webhook)

I have tried:

      mp = Multipart.new()
        |> Multipart.add_field("url", "https://my-sever-ip:88/bots/#{token}")
        |> Multipart.add_field("certificate", "bots.pem")
        |> Multipart.add_file(file, name: "bots.pem")

      post("bot#{token}/setwebhook", mp)

But the operation is not successful.

Please how may I achieve the same as this : https://paperlesssolutionsltd.com.ng/bots.htm manual file upload utility using Tesla.

Thanks.