Version 2.3.2 -> Version 2.4.0 (Proposed): Update React & React-Dom to 17.0.1.

[DoctorDerek]

This closes issue #70. This PR is an alternative to PR #68 and would update the semver of use-dark-mode from 2.3.2 to 2.4.0 to reflect the new peer dependency (React ^16.8 -> React ^17.0.1).

No code needs to be changed, as existing use-dark-mode v2.3.1 works fine with React 17; see: https://codesandbox.io/s/usedarkmode-demo-forked-fo70t?file=/src/App.js (But I took out the import React from "react" statement! ha!)

[bakon11]

It would be great if one of the maintainers could merge this, I hate having to use --force or --ignore.

Thanks.

[adriangzz]

Can we get this merged? @donavon