How can I sum hourly data from 01:00 of the month to the hour 00:00 of the next month?

Question

I have this data:

2020-08-01 00:00:00-05:00   70.805809
2020-08-01 01:00:00-05:00   66.828538
2020-08-01 02:00:00-05:00   69.250954
2020-08-01 03:00:00-05:00