input: Write a function to convert a date string into the day of the week.
  assert get_day_of_week("21 October 2020") == "Wednesday"
  assert get_day_of_week("1 January 2022") == "Saturday"
  assert get_day_of_week("4 July 2021") == "Sunday"
output: def get_day_of_week(date_str):
      from datetime import datetime
      date_obj = datetime.strptime(date_str, "%d %B %Y")
      return date_obj.strftime("%A")