a8n: Changeset review state is "changes requested" even if reviewer changed to "approved"
Created by: mrnugget
I added https://github.com/sourcegraph/sourcegraph/pull/5847 to a campaign and its status was displayed as "changes requested"
But the reviewer (me) added another review with status "approved":
In that case we need to do the same thing that we do for the burndown chart in #5895 and only use the latest review per reviewer to compute the overall review state