private void ButtonUpdatePack_Click(object sender, RoutedEventArgs e)
        {
            Pack pack = (Pack)ListPack.SelectedItem;

            if (pack != null)
            {
                PackWindow packWindow = new PackWindow(db);
                packWindow.DataContext = pack;
                packWindow.ShowDialog();

                if (packWindow.DialogResult == true)
                {
                    db.SaveChanges();
                }
            }
            else
            {
                MessageBox.Show("Vous n'avez séléctionné aucun client.");
            }
        }
        private void ButtonAddPack_Click(object sender, RoutedEventArgs e)
        {
            Pack pack = new Pack();
            PackWindow packWindow = new PackWindow(db);

            packWindow.DataContext = pack;
            packWindow.ShowDialog();

            if (packWindow.DialogResult == true)
            {
                Packs.Add(pack);
                db.Pack.Add(pack);

                db.SaveChanges();
            }
        }