I'm updating segmented-control to React 17 and would need Formsy to support it as well.

There must be a lot of community members who are starting to need React 17 support for their own projects too.

I tried to work on it but quickly got stopped in my tracks because airbnb-prop-types still requires React 16, although that's about to change soon thanks to this PR.

Just filing this issue to:

1. Track progress of React 17 support on airbnb-prop-types
2. For anyone else to work on React 17 support themselves if I don't have time to do it