input: Write a python function to convert date format from "DD-MM-YYYY" to "MM-DD-YYYY".
  assert convertDateFormat("12-31-2020")=="31-12-2020"
  assert convertDateFormat("01-15-2021")=="15-01-2021"
  assert convertDateFormat("11-05-1990")=="05-11-1990"
output: def convertDateFormat(date):
      day, month, year = date.split('-')
      return f"{month}-{day}-{year}"