error-stack@0.8.0

What changed

Breaking Changes

• Fix a soundness hole in Report::frames_mut: the returned iterator handed out &mut Frames with independent lifetimes, so a frame and one of its sources (via Frame::sources_mut) could be borrowed mutably at the same time — undefined behavior triggerable from safe code, up to segfaults. frames_mut now takes a visitor closure (FnMut(&mut Frame) -> ControlFlow<()>) instead of returning an iterator, and the FramesMut type has been removed. Report::downcast_mut is unaffected. (#8946)