__hash__ = None in class definition should not emit assignment error

[starhel]

Bug Report
To suppress hash support in a class, it's recommended to include __hash__ = None in the class definition (it's also required by the ruff rule PLW1641). Unfortunately, mypy reports it as an error.

error: Incompatible types in assignment (expression has type "None", base class "object" defined the type as "Callable[[object], int]")  [assignment]

To Reproduce
https://mypy-play.net/?mypy=latest&python=3.12&gist=2f1c3fd7eff039975b0203c916d75002

class A:
    __hash__ = None

    def __init__(self, x):
        self.x = x

a = A(10)

[JukkaL]

Closing as duplicate of #4266.