cross-fetch 4.0.0 on Node.js NPM

What's Changed

BREAKING CHANGES

Dropped support for Node 10 and 12. (Note: cross-fetch will likely continue working on those versions, but specs tests are not running on those Node versions and no support will be provided if issues come up.)
Please check implementation conflicts in the Fetch API tests.

FEATURES

Added support for Node 18 and 20.
Added support for Service and Cloudflare Workers (Fixes #69, #78, #148) by prioritizing native code over third-party implementation. Fetch API test suite now running against node-fetch, whatwg-fetch, native browser and native node fetch.
Upgraded whatwg-fetch to 3.6.2. Please refer to whatwg-fetch release notes between 3.0.0 and 3.6.2 for features and bug fixes.
fetch.ponyfill is set to true when custom implementation is used. This improves debuggability.