Version 16.6.0

• Added parentNode.replaceChildren(). (@ninevra)
• Fixed jsdom's handling of when code running inside the jsdom throws null or undefined as an exception. (@mbest)
• Removed the dependency on the deprecated request package, in the process fixing several issues with the XMLHttpRequest implementation around header processing. Thanks go to @tobyhinloopen, @andrewaylett, and especially @vegardbb, for completing this months-long effort!