Update main: use http.PostForm instead of http.Do

main.go

@@ -174,13 +174,9 @@ func main() {
 			data.Set("refresh_token", refreshToken)
 			data.Set("grant_type", "refresh_token")
 		}
-		
-		client := &http.Client{}
-		req, _ := http.NewRequest("POST", tokenUrl, strings.NewReader(data.Encode()))
-		req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
 
 		fmt.Println(time.Now().Format("2006-01-02 15:04:05"), "- Send request to token endpoint", tokenUrl)
-		response, err := client.Do(req)
+		response, err := http.PostForm(tokenUrl, data)
 		fmt.Println(time.Now().Format("2006-01-02 15:04:05"), "- Endpoint response with status", response.Status)
 		if err != nil {
 			fmt.Println(err)