如何使用gorequest发出POST请求

Reddit has an API endpoint for Oauth2 where I need to do POST with proper headers and data to get the access token. Here is my code:

package main

import (
    "github.com/parnurzeal/gorequest"
    "fmt"
)

func main() {
    app_key := "K...A"
    app_secret := "3...M"
    ua_string := "script:bast:0.1 (by /u/a...h)"
    username := "a...h"
    password := "..."
    r := gorequest.New().SetBasicAuth(app_key, app_secret).Set("User-Agent", ua_string)
    resp, body, errs := r.Post("https://www.reddit.com/api/v1/access_token").Send(
        map[string]string{
            "grant_type": "password",
            "username": username,
            "password": password,
        },
    ).End()
    if errs != nil {
        fmt.Println(errs)
    }
    fmt.Println(resp)
    fmt.Println(resp.StatusCode)
    fmt.Println(body)
}

However it's not working and I am getting: {"message": "Too Many Requests", "error": 429}

I am not making too many requests at all and I am following the API rules too.

Here is my equivalent python code which works:

import requests
import requests.auth

app_key = "K...A"
app_secret = "3...M"
ua_string = "script:bast:0.1 (by /u/a...h)"
username = "a...h"
password = "..."

client_auth = requests.auth.HTTPBasicAuth(app_key, app_secret)
post_data = {"grant_type": "password", "username": username,
             "password": password}
headers = {"User-Agent": ua_string}
response = requests.post("https://www.reddit.com/api/v1/access_token",
                         auth=client_auth, data=post_data, headers=headers)
print(response.json())

So whats wrong with my Go code? Is there any mistake I am doing?

I have been using paw client, mainly because I can test/debug my request and once I am done, I can obtain curl or go code for doing so, besides other options, for example this is an output for doing a generic post request:

package main

import (
    "fmt"
    "io/ioutil"
    "net/http"
)

func sendGetRepos() {
    // Create client
    client := &http.Client{}

    // Create request
    req, err := http.NewRequest("POST", "https://api.endpoint.tld", nil)

    // Headers
    req.Header.Add("Authorization", "Bearer ***** Hidden credentials *****")

    // Fetch Request
    resp, err := client.Do(req)

    if err != nil {
        fmt.Println("Failure : ", err)
    }

    // Read Response Body
    respBody, _ := ioutil.ReadAll(resp.Body)

    // Display Results
    fmt.Println("response Status : ", resp.Status)
    fmt.Println("response Headers : ", resp.Header)
    fmt.Println("response Body : ", string(respBody))
}