enum auto must not be derived from IntFlag

When using auto enumeration within an class Example(enum.Enum): X = auto(), the invokation of auto() is actually constructing an instance of enum.auto, which just has a default constructor without any extra arguments.

However, when deriving class auto(IntFlag) in enum.pyi the stub actually has a constructor argument of type int, the value for the IntFlag.

This contradicts the definition in the original enum.py implementation.
As a matter of fact this leads to confusing type hints, e.g. enum class auto(IntFlag).

首先，将 enum.pyi 中 auto 的定义与 issue 中提到的原始 enum.py 实现进行比较。检查两个文件中显示的构造函数和继承关系，然后更新 stub，使其定义与实现一致，并且不再生成令人困惑的类型提示 enum.auto(IntFlag)。