Update CHANGELOG-EE.md for 13.0.6-ee

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CHANGELOG-EE.md

 Please view this file on the master branch, on stable branches it's out of date.
+## 13.0.6 (2020-06-10)
+
+### Security (1 change)
+
+- Do not set fallback mirror user.
+
+
 ## 13.0.4 (2020-06-03)
 - No changes.

ee/changelogs/unreleased/security-163-mirror-user.yml

----
-title: Do not set fallback mirror user
-merge_request:
-author:
-type: security