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)?