qwert

with open('import.csv', newline='') as source:
    reader = csv.DictReader(source)
    with open('export.csv', mode='w', encoding='utf-8-sig', newline='') as destination:

        writer = csv.DictWriter(destination, dialect=csv.unix_dialect, fieldnames=reader.fieldnames)
        writer.writeheader()
        writer.writerows(
            filter(lambda x: x.get('date') not in weekend_days, reader)
        )