[Integrated] RFR: pr-bot: add contributors to summary

[Erik Helin]

Changeset: 3857844a
Author:    Erik Helin <ehelin at openjdk.org>
Date:      2020-02-13 12:59:44 +0000
URL:       https://git.openjdk.java.net/skara/commit/3857844a

pr-bot: add contributors to summary

Reviewed-by: rwestberg

! bots/pr/src/main/java/org/openjdk/skara/bots/pr/CheckRun.java
! bots/pr/src/main/java/org/openjdk/skara/bots/pr/PullRequestBot.java
! bots/pr/src/test/java/org/openjdk/skara/bots/pr/ContributorTests.java