flow semver 6.2 -> 7 type defintions (#45495)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/45495

Unify type definitions to semver@7, to fix a [type-sync](https://www.internalfb.com/intern/test/281475050813096/) test that was broken by D59378011.  The test is very simple and doesn't actually understand the typing.

I don't believe there is a significant difference in the typing, esp. with how we're using it.  Flow will tell us if this is the case though (🏖️ 🏰).

Changelog: [Internal]

Reviewed By: huntie

Differential Revision: D59855434

fbshipit-source-id: ae3c6b7aa81b3cde25468d72a7922bcb2b6f652f