Update CHANGELOG-EE.md for 13.8.3-ee

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CHANGELOG-EE.md

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+## 13.8.3 (2021-02-05)
+
+### Fixed (2 changes)
+
+- Fix Geo replication and verification status for replicables with no data to sync. !52253
+- Handle network unreachable for ES settings check. !52586
+
+
 ## 13.8.2 (2021-02-01)
 
 ### Security (2 changes)

ee/changelogs/unreleased/298725-gitlab-ctl-promotion-preflight-checks-incorrectly-fails-with-0.yml

----
-title: Fix Geo replication and verification status for replicables with no data to
-  sync
-merge_request: 52253
-author:
-type: fixed

ee/changelogs/unreleased/299991-opening-admin-settings-page-results-in-the-error-500-if-localho.yml

----
-title: Handle network unreachable for ES settings check
-merge_request: 52586
-author:
-type: fixed