Flow errors with npm

[zinoviev]

The last PR builds failed with flow errors on promise package

I spot these on last two PR #569 and #677 and it's true for master as well

On my local environment, everything is fine with yarn but doesn't work with npm
Promise is fbjs dependency ^7.03, with yarn it's resolved with 7.1.1 version for npm it's 7.3.0

7.3.0 promise kills our build
then/promise#135

Not sure how to deal with it - wait for promise team for fix or pin promise version in fbjs

[ForbesLindesay]

This should now be resolved.

[bvaughn]

Can confirm, CI seems happy now. Thanks for the update, @ForbesLindesay!