Include missing "dont-cleanup-after-each" script in npm package

[ndresx]

What:

This adds the currently missing dont-cleanup-after-each.js file reference in package.json so that npm can pick it up and ship it within an upcoming release.

Why:

According to the docs (https://react-hooks-testing-library.com/reference/api#cleanup), it should be possible to set up this script via Jest config, but the file doesn't exist in the current package version (https://www.unpkg.com/browse/@testing-library/[email protected]/).

It also removes the redundant README.md and LICENSE.md from the files list as they are always included on npm publish (https://docs.npmjs.com/files/package.json#files).

Checklist:

• Ready to be merged
  

[codecov]

Codecov Report

Merging #208 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #208   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           2      2           
  Lines          56     56           
  Branches        5      5           
=====================================
  Hits           56     56

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[mpeyper]

Wow. Whoops!

Thanks for spotting that and fixing it!