input: Write a python function to filter numbers greater than or equal to 5 from a list.
  assert filter_numbers([1, 4, 6, 8, 10, 15, 20]) == [6, 8, 10, 15, 20]
  assert filter_numbers([5, 3, 9, 12, 1]) == [5, 9, 12]
  assert filter_numbers([2, 4, 6, 8]) == [6, 8]
output: def filter_numbers(numbers):
      return [num for num in numbers if num >= 5]