Suggestion: update `ensure_ascii` to `False`

[senyai]

All modern json parsers can understand utf-8 encoding, so it feels to me that default ensure_ascii=True should be a thing of the past.

[dpranke]

If we were starting from scratch and didn't have existing implementations to worry about, I'd probably agree with you.

However, if I was to change it now, that could break existing code. Perhaps more importantly, I try to match the built-in json behavior where I can, and that also defaults to ensure_ascii=True.

So I don't think it'd be a great idea to change this. If the json module changes things, though, I might be inclined to revisit this.