input: Write a python function to convert a list of strings to a list of integers.
  assert convert_to_integers(['1', '2', '3']) == [1, 2, 3]
  assert convert_to_integers(['10', '20', '30']) == [10, 20, 30]
  assert convert_to_integers(['5', '7', '9', '0']) == [5, 7, 9, 0]
output: def convert_to_integers(lst):
      return [int(x) for x in lst]