[RN0.66] 41/n: Patch Easing types

Summary: This is what Facebook did, so we'll do the same. It will be fixed in React Native 0.68 with this patch.

Test Plan: Flow

Reviewers: palys-swm, atul

Reviewed By: palys-swm

Subscribers: benschac, Adrian, karol-bisztyga

Differential Revision: https://phabricator.ashoat.com/D3022