MAINT: cleanup the lasts of datetime.utcnow()

MAINT: cleanup the lasts of datetime.utcnow()

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### Description
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I'm chasing some loose datetime.datetime.utcnow() deprecation warning in some test suites, and one of these was seemingly coming from sqlalchemy. It wasn't, but nevertheless these minor cleanup changes may still be found useful.

### Checklist
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This pull request is:

- [x] A documentation / typographical / small typing error fix
	- Good to go, no issue or tests are needed

**Have a nice day!**

Closes: #11736
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/11736
Pull-request-sha: 9bee8af8d1082c3cde5f64c78f1e565ef4ab14cd

Change-Id: Ib1b85fa3d66b665165d908e7c8394482b714c57f
(cherry picked from commit 6fefae897a576bce9ec74101e3a5ebcda0557c00)