Import payments is missing content-type header

[Tetragramat]

Request POST "https://fioapi.fio.cz/v1/rest/import/" is being send without header Content-Type: multipart/form-data.

That means payment imports don't work and end with 400 Bad Request and html content containing Required request parameter 'token' for method parameter type String is not present.

[h4kuna]

I fixed. If I use GuzzleHttp\Psr7\MultipartStream, the guzzle automaticaly set header multipart with right boundary. If you use symfony client, you found the bug. Could you try master. I tested too :)

[h4kuna]

fixed v3.0.11