refactor: moved to compatible with React 17

[semoal]

• Changed peerDeps to react 15,16,17. If we update react-transtion-group to ^3 | 4^ we must release a breaking change because drops compatibility with react 15
• Removed karma,chai,enzyme blablabla... and used only Jest and Testing-Library.
• Updated devDependencies and cleared some.

Checks: ✅ npm run test ✅ npm run lint ✅ npm run demo -> 4 examples are correctly rendered

Questions: ❓ Should I create a Github Action file? Looks more interesting than Travis, that looks isn't working on pull requests. I have already one ready if you're comfortable with github actions i push one

Master branch:

ReactSmooth.min.js  58.9 KiB       0  [emitted]  main

This branch:

ReactSmooth.min.js  35.6 KiB       0  [emitted]  main

[semoal]

@xile611 this pull request is ready, I can revert the lodash move if you don't feel "safe", i've tried this package in my projects and works good, but as you consider.

Also... probably could be a good idea to drop React 15 support and upgrading react-transition-group to 4.x.x?

[pm-mkorpar]

Any update on this? :)