private void textBoxKerko_TextChanged(object sender, EventArgs e)
        {
            string keyword = textBoxKerko.Text;

            dataGridViewKokeFurnizimiList.DataSource = kf.KerkoKokeFurnizimi(keyword);
            if (keyword == "")
            {
                DataTable viziteData = kf.SelectKokeFurnizimi();
                dataGridViewKokeFurnizimiList.DataSource = viziteData;
            }
        }