func main() {
    //...

    // create HTTP request
    req, err := http.NewRequest("GET", "https://httpbin.io/user-agent", nil)
    if err != nil {
        // Handle error
        return
    }

    // set User-Agent header
    req.Header.Set("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36")
}