Relax the signature of logging.config.loadConfig

[JukkaL]

I did a a cursory investigation using GitHub search and also looked at
a big internal codebase, and a significant fraction of callsites used
a dict type instead of a TypedDict or a dict literal.

It seems that it's a common use case to store the config within an
attribute. For example, something like this:

CONFIG = {
   ...
}

...
logging.config.dictConfig(CONFIG)

Another use case that was not properly supported is reading the
config from a file, and the config is given dict[str, Any] as
the type.

Mypy can still do some type checking of the argument if called
with a dict literal, so I feel this is a reasonable compromise
between type checking strictness and usability.

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉