input: Write a python function to filter numbers less than or equal to 5 from a list.
  assert filter_numbers([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) == [1, 2, 3, 4, 5]
  assert filter_numbers([10, 20, 45, 4, 2, 5, 1]) == [4, 2, 5, 1]
  assert filter_numbers([5, 7, 9, 8, 6, 4, 3]) == [5, 4, 3]
output: def filter_numbers(lst):
      return [num for num in lst if num <= 5]