What kind of change does this PR introduce?

• Bug Fix
• Feature
• Refactoring
• Style
• Build
• Chore
• Documentation
• CI

Did you add tests for your changes?

• Yes, my code is well tested
• Not relevant

If relevant, did you update the documentation?

• Yes, I've updated the documentation
• Not relevant

Summary

Follow up to #1382. Attempt to fix the publint warnings:

➜  npx publint
react-dropzone lint results:
Suggestions:
1. The package does not specify the type field. NodeJS may attempt to detect the package type causing a small performance hit. Consider adding "type": "commonjs".
2. pkg.repository.url is https://github.com/react-dropzone/react-dropzone.git but could be a full git URL like "git+https://github.com/react-dropzone/react-dropzone.git".
3. The package publishes internal tests or config files. You can use pkg.files to only publish certain files and save user bandwidth.
Warnings:
1. pkg.exports["."].import.types types is interpreted as CJS when resolving with the "import" condition. This causes the types to be ambiguous when default importing the package due to its implied interop. Consider splitting out two "types" conditions for "import" and "require", and use the .mts extension, e.g. pkg.exports["."].import.import.types: "./typings/react-dropzone.d.mts"
2. pkg.exports["."].import.default is ./dist/es/index.js and is written in ESM, but is interpreted as CJS. Consider using the .mjs extension, e.g. ./dist/es/index.mjs

Does this PR introduce a breaking change?

It shouldn't, but I'm unable to test across browsers and different environments to tell for sure.

Other information

There were/are a few other changes/challenges while attempting to fix the warnings:

1. Setting the type to module in package.json would most likely result in no support for commonjs, so instead, we used the mjs extension for the es distribution (which was one of the warnings)
2. Tests would not longer work because of the above change, and after spending some time trying to fix it, what worked was switching to @swc/jest as a transform and a few other settings described in jest's ECMAScript Modules doc
3. The other consequence was that eslint had to be updated too; so there are some changes around upgrading some of the packages and migrating to flat configs (this is WIP)
4. We may not be able to go fwd with this if we stick to react-styleguidist; it currently does not build on the latest or current version; some additional work is required to see if we can make it work (webpack-blocks cannot be used, its deps are too old if we want to update webpack for react-styleguidist - some work around that started in https://github.com/react-dropzone/react-dropzone/tree/chore/update-deps)