v21.0.0 - Back to the Future

Docs:

• bf50c1f- Chinese docs up to date with the latest English source. Thanks @mk965! 🎉

Possibly Breaking Change:

• 283e66e - An exports field was added to package.json to make it compatible with ESM tools (to override the main field currently pointing at a CommonJS file which doesn't make sense for ESM, but does for old Node.js). To be safe, we made this a major version because there's a chance it can break someone's app (f.e. if they imported from dist/ directly, that will now be blocked, and they would need to change import ... from '@tweenjs/tween.js/dist/tween.esm.js' to import ... from '@tweenjs/tween.js'). Thanks for this @christjt!