Update CHANGELOG (flutter#176654)

Updates `CHANGELOG` to include the two cherry picks in the 3.35.6 hotfix stable release:

flutter#176520
flutter#176359

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Author: camsim99

CHANGELOG.md

@@ -32,9 +32,10 @@ docs/releases/Hotfix-Documentation-Best-Practices.md
 
 ## Flutter 3.35 Changes
 
-### [3.35.5](https://github.com/flutter/flutter/releases/tag/3.35.5)
+### [3.35.6](https://github.com/flutter/flutter/releases/tag/3.35.6)
 
-[flutter/175669](https://github.com/flutter/flutter/issues/175669) Flutter analyze --suggestions supports versions up to Java 25, Gradle 9 and AGP 9, Kotlin 2.2.20.
+- [flutter/175669](https://github.com/flutter/flutter/issues/175669) `flutter analyze --suggestions` supports versions up to Java 25, Gradle 9 and AGP 9, Kotlin 2.2.20.
+- [flutter/172624](https://github.com/flutter/flutter/issues/172624) Fixes an issue that could result in a corrupt pipeline cache when using the Impeller Vulkan back end.
 
 ### [3.35.5](https://github.com/flutter/flutter/releases/tag/3.35.5)