Update CHANGELOG.md

Author: calvincestari

apollo-ios/CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## v1.25.3
 
+### Fixed
+
+- **Include merged fields in selection set equality check ([#3602](https://github.com/apollographql/apollo-ios-dev/issues/3602)):** When a field merged from a child object in a named fragment was merged, it was not being used for equality checks. Equality checks now use the types `__fulfilledFragments` and collects selections from all of them, instead of just traversing downward from `self.__selections`. This ensures all expected data is collected from merged fragments. See PR [#832](https://github.com/apollographql/apollo-ios-dev/pull/832). _Thank you to [@JOyo246](https://github.com/JOyo246) for raising the issue_.
 
 ## v1.25.2