Finding the midpoint between values in a pandas datetime column and making a start and end time period column based on the midpoint

Question

Here is my code set up:

import pandas as pd
    
    df = {\'Datetime\':  [\'2020-12-01 00:00:00\', \'2020-12-01 01:00:00\',\'2020-12-01 02:00:00\',