chore: Add React ^16.8 and ^17 to peer deps.

[horseeyephil]

PR:

Discussion: #391

Adds more versions of React so that projects that don't use 18 may install embla-carousel-react without errors of the missing peer dependency. This would usually require --force or --legacy-peer-deps to bypass.

Validation:

• Forked repo and add commit: https://github.com/horseeyephil/embla-carousel/commits/master
• Used gitpkg (https://gitpkg.vercel.app/) to point to the packages/embla-carousel-react subdirectory.
  Install as such: npm install 'https://gitpkg.now.sh/horseeyephil/embla-carousel/packages/embla-carousel-react?master'
• Install into a new project using React 17 as a dependency in package.json. The usual peer dependency error is not apparent.
• Validate: Change the dependency from React 17 to React 15 (outside of the new range). Observe errors (or warning if using Yarn):

[davidjerleke]

Thank you very much @horseeyephil for this PR and taking time to test this. Welcome to the contributors club ⭐!