Warn against `metaclass=type`

[JelleZijlstra]

Summary

type is the default metaclass and adding metaclass=type is usually redundant.

Example in python/typeshed#14150. This is similar to https://docs.astral.sh/ruff/rules/useless-object-inheritance/ about inheriting from object.

[chirizxc]

@MichaReiser can you assign this to me?

[chirizxc]

and what should the rule code be?

[fennr]

There is already a rule https://docs.astral.sh/ruff/rules/useless-metaclass-type/
It seems to be worth adding a check in it.

[JelleZijlstra]

@fennr That's a little different as it's about the Python 2 idiom with __metaclass__.

[MichaReiser]

and what should the rule code be?

You can added it using the next available UP code.

For why this rule

Even though prepare is not required, the default metaclass (‘type’) implements it, for the convenience of subclasses calling it via super().
source https://peps.python.org/pep-3115/