Correct response headers
Correct response headers

> ## 5.3 Processing Model
>
> [...]
>
> When required to send a response, with arguments status and data, a
> remote end must run the following steps:
>
> [...]
> 3. Set the response's header with name and value with the following
>    values:
>
>    "Content-Type"
>        "application/json; charset=utf-8"
>    "cache-control"
>        "no-cache"

Source: https://w3c.github.io/webdriver/webdriver-spec.html#dfn-send-a-response

AutomatedTester/webdriver-rust