我用Go編寫了這個API，它使用excelize創建一個.xlsx文件，從數據庫中獲取的數據，我想上傳到私有GCS存儲桶。但問題是在我上傳文件后，它說文件類型不是 。application/zipapplication/vnd.openxmlformats-officedocument.spreadsheetml.sheettype Connection struct {    Credential    string    BucketName    string    APIKey        string    ProjectID     string    AccessToken   string    BaseURL       string    GcpCredential *google.Credentials}func (conn *Connection) Upload(url, name string) (err error) {    ctx := context.Background()    client, err := storage.NewClient(ctx, option.WithCredentialsFile(conn.Credential))    if err != nil {        return err    }    err = write(client, conn.BucketName, name, url)    return err}func write(client *storage.Client, bucket, object, url string) error {    ctx := context.Background()    f, err := os.Open(url)    if err != nil {        return err    }    defer f.Close()    wc := client.Bucket(bucket).Object(object).NewWriter(ctx)    _, err = io.Copy(wc, f)    if err != nil {        return err    }    if err := wc.Close(); err != nil {        return err    }    return nil}//In other file, generate excel file and upload it using above codexlsx := excelize.NewFile()//setup file content...//save to local machine located in uploadURLerr = xlsx.SaveAs(uploadURL)//then upload to GCS bucketerr = h.Googlestorage.Upload(uploadURL, fileNameInGCS)if err != nil {    SendBadRequest(w, err.Error())    return}//then generate signed URL for client to access the file這是一個問題，因為當我生成文件的簽名URL時，它被下載為.zip文件，而不是.xlsx。"{file path in bucket}.xlsx?Expires=1617698911&GoogleAccessId={googleAccessID}&Signature={someGeneratedSignature}"如何解決此問題？我上傳文件的方式有問題嗎？