node has defined `structuredClone` in v19 and v20, and jest-environment-node is polyfilling it improperly

[bgrnwd]

The trouble seems to be that node has defined structuredClone in v19 and v20, and jest-environment-node is polyfilling it improperly. We don't use the function anywhere, so we can define it ourselves and it'll work. I expect we'll see a fix in the future to jest-environment-node that'll make it so we don't have to include this line -- maybe we should add an issue or something to follow up on this in the future?

Originally posted by @doug-wade in #31 (comment)