Update CHANGELOG entries for 3.13.2 release

Author: hehe7318

CHANGELOG.md

@@ -7,7 +7,7 @@ This file is used to list changes made in each version of the AWS ParallelCluste
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 **CHANGES**
-- Fix build image failures occurring on non-latest versions of Rocky Linux 9.
+- Fix `build-image` failure on Rocky 9, occurring when the parent image is not the latest version. https://github.com/aws/aws-parallelcluster/issues/6874
 
 3.13.1
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