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: 9bee8af8d1

Change-Id: Ib1b85fa3d66b665165d908e7c8394482b714c57f

examples/extending_query/temporal_range.py

@@ -5,6 +5,7 @@ to selected entities.
 """
 
 import datetime
+from functools import partial
 
 from sqlalchemy import Column
 from sqlalchemy import create_engine
@@ -23,7 +24,9 @@ class HasTemporal:
     """Mixin that identifies a class as having a timestamp column"""
 
     timestamp = Column(
-        DateTime, default=datetime.datetime.utcnow, nullable=False
+        DateTime,
+        default=partial(datetime.datetime.now, datetime.timezone.utc),
+        nullable=False,
     )
 
 

lib/sqlalchemy/orm/events.py

@@ -3135,7 +3135,9 @@ class QueryEvents(event.Events[Query[Any]]):
                         entity = desc['entity']
                         query = query.filter(entity.deleted == False)
 
-                        update_context.values['timestamp'] = datetime.utcnow()
+                        update_context.values['timestamp'] = (
+                            datetime.datetime.now(datetime.UTC)
+                        )
                 return query
 
         The ``.values`` dictionary of the "update context" object can also

test/orm/test_relationship_criteria.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import datetime
+from functools import partial
 import random
 from typing import List
 
@@ -1661,7 +1662,9 @@ class TemporalFixtureTest(testing.fixtures.DeclarativeMappedTest):
             """Mixin that identifies a class as having a timestamp column"""
 
             timestamp = Column(
-                DateTime, default=datetime.datetime.utcnow, nullable=False
+                DateTime,
+                default=partial(datetime.datetime.now, datetime.timezone.utc),
+                nullable=False,
             )
 
         cls.HasTemporal = HasTemporal