fix: update utcnow for python 3.12 deprecation #55

Job	Run time
Tests (3.9)	21s
Tests (3.11)	23s
Tests (3.10)	18s
Individual Backend Smoketests (quart)	15s
Flake8	21s
Individual Backend Smoketests (fastapi)	23s
Tests (3.13)	19s
Individual Backend Smoketests (sanic)	17s
Tests (3.8)	23s
Tests (3.12)	22s
Individual Backend Smoketests (flask)	13s
	3m 35s

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