input: Write a function to convert a list of strings to a list of floats.
  assert str_to_float(["1.1", "2.2", "3.3"]) == [1.1, 2.2, 3.3]
  assert str_to_float(["4.4", "5.5", "6.6"]) == [4.4, 5.5, 6.6]
  assert str_to_float(["7.7", "8.8", "9.9"]) == [7.7, 8.8, 9.9]
output: def str_to_float(lst):
      return [float(i) for i in lst]