The datetime.datetime.utcnow() switcheroo

I mention `dt.datetime.utcnow()` here:

https://github.com/amontalenti/elements-of-python-style#the-standard-library

Looks like this is deprecated in Python 3.12. Covered well by Miguel Grinberg here:

https://blog.miguelgrinberg.com/post/it-s-time-for-a-change-datetime-utcnow-is-now-deprecated