Added missing changelog for 12.10.13

CHANGELOG.md

@@ -189,6 +189,13 @@ omnibus-gitlab repository.
 - Update Mattermost to 5.22.2. (Harrison Healey)
+## 12.10.13 (2020-07-01)
+
+### Security (1 change)
+
+- Update PCRE to version 8.44.
+
+
 ## 12.10.12 (2020-06-24)
 ### Fixed (2 changes)