Request: Update/Remove `prop-types` Usage

• downshift version: 9.0.6
• node version: 20.11.1
• npm (or yarn) version: Yarn 4.2.2

Problem description:

I'm getting the following earning: "Failed prop type: The prop environment.document.activeElement is marked as required, but its value is null". As mentioned in https://developer.mozilla.org/en-US/docs/Web/API/Document/activeElement + the TS types, this value is nullable.

Suggested solution:

We could just update the relevant prop types to not have this marked as required, but looking at the bigger picture - do we still see value in providing prop types at all? Could these be removed in v10 (https://github.com/downshift-js/downshift/issues/1588)?