How to authenticate the Pardot API using HttpClient

Question

I struggled for about a day trying to authenticate against the Pardot API. It didn't like how I was trying to post the message body. So I wanted to post the solution that worked for me. If you have any tips or alternatives I'd like to hear them.

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls;

var url = "https://pi.pardot.com/api/login/version/3";

//(Edit) Shorter way to pass the parameters below
//var postData = new List<KeyValuePair<string, string>>
//{
//    new KeyValuePair<string, string>("email", "<value>"),
//    new KeyValuePair<string, string>("password", "<value>"),
//    new KeyValuePair<string, string>("user_key", "<value>")
//};

var postData = new Dictionary<string, string>
{
    {"email", "<value>"},
    {"password", "<value>"},
    {"user_key", "<value>"}
};

var httpContent = new FormUrlEncodedContent(postData);

using (var client = new HttpClient())
{
    HttpResponseMessage response = client.PostAsync(url, httpContent).Result;

    if (response.IsSuccessStatusCode)
    {
        string resultValue = response.Content.ReadAsStringAsync().Result;
    }
}

Thanks!