Upgrade black version (#7089)

stdlib/itertools.pyi

@@ -58,6 +58,7 @@ class accumulate(Iterator[_T], Generic[_T]):
         def __init__(self, iterable: Iterable[_S], func: Callable[[_T, _S], _T], *, initial: _T | None = ...) -> None: ...
     else:
         def __init__(self, iterable: Iterable[_T], func: Callable[[_T, _T], _T] | None = ...) -> None: ...
+
     def __iter__(self) -> Iterator[_T]: ...
     def __next__(self) -> _T: ...