Replace datetime.utcfromtimestamp with datetime.fromtimestamp
This MR replaces the usage of datetime.datetime.utcfromtimestamp with a timezone-aware use of datetime.datetime.fromtimestamp; the former method is deprecated in Python 3.12.
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This MR replaces the usage of datetime.datetime.utcfromtimestamp with a timezone-aware use of datetime.datetime.fromtimestamp; the former method is deprecated in Python 3.12.