[PyQt] manage display date

[Gribouillis]

The built-in module datetime is always helpful when handling dates and time

import datetime as dt

def insert_date(self):
    try:
        d = int(self.lineEdit_day.text())
        m = int(self.lineEdit_month.text())
        y = int(self.lineEdit_year.text())
        date = dt.date(y, m, d)
    except ValueError:
        self.textEdit_error_display.setText("invalid fields")
    else:
        self.lineEdit_date_introduced.setText("{:%d/%m/%Y}".format(date))