input: Write a python function to sort a list in ascending order using bubble sort.
  assert sort_list([3, 7, 1, 4, 5])==[1, 3, 4, 5, 7]
  assert sort_list([10, 2, 8, 6, 7])==[2, 6, 7, 8, 10]
  assert sort_list([5, 3, 2, 4, 1])==[1, 2, 3, 4, 5]
output: def sort_list(arr):
      n = len(arr)
      for i in range(n):
          for j in range(0, n-i-1):
              if arr[j] > arr[j+1]:
                  arr[j], arr[j+1] = arr[j+1], arr[j]
      return arr