Merge branch 'update-doorkeeper-changelog' into 'master'

Add changelog entry for updating doorkeeper

See merge request gitlab-org/gitlab-ce!18550

changelogs/unreleased/update-doorkeeper-changelog.yml

+---
+title: Update doorkeeper to 4.3.2 to fix GitLab OAuth authentication
+merge_request: 18543
+author:
+type: fixed