private void BookSearchBar_TextChanged(object sender, TextChangedEventArgs e)
{
var searchDonationResult = DonationAdverts.Where(c => c.BookName.ToLower().Contains(BookSearchBar.Text.ToLower()));
var searchExchangeResult = ExchangeAdverts.Where(c => c.BookName.ToLower().Contains(BookSearchBar.Text.ToLower()));
DonationsListView.ItemsSource = searchDonationResult;
ExchangesListView.ItemsSource = searchExchangeResult;
}
