`utcnow` deprecation note is misleading

Documentation

Currently, the deprecation notice for datetime.utcnow() reads:

Deprecated since version 3.12: Use datetime.now() with UTC instead.

Unfortunately, applying this suggestion verbatim can easily break user code – especially when applying it to libraries. (See for example https://foss.heptapod.net/openpyxl/openpyxl/-/issues/2051). These datetime-related TypeErrors are easy to introduce, and fairly hard to fix. I suggest to amend the deprecation notice:

Deprecated since version 3.12: Use datetime.now(UTC) instead. Please note that this will return an aware datetime object. If you need to remain compatible, use datetime.now(UTC).replace(tzinfo=None).

Maybe someone can come up with a better wording.

Linked PRs

• gh-118571

Revise a documentação de datetime.datetime.utcnow() na página datetime vinculada e compare a redação proposta com o PR gh-118571. Considera-se concluído quando a nota de depreciação alertar claramente que datetime.now(UTC) retorna um aware datetime e declarar a opção de compatibilidade replace(tzinfo=None), ou adotar uma redação melhor acordada.