Add BaseException.__new__ (#12346)

Author: tomasr8

stdlib/builtins.pyi

@@ -1868,6 +1868,7 @@ class BaseException:
     __suppress_context__: bool
     __traceback__: TracebackType | None
     def __init__(self, *args: object) -> None: ...
+    def __new__(cls, *args: Any, **kwds: Any) -> Self: ...
     def __setstate__(self, state: dict[str, Any] | None, /) -> None: ...
     def with_traceback(self, tb: TracebackType | None, /) -> Self: ...
     if sys.version_info >= (3, 11):