Update CHANGELOG.md

Author: averikitsch

CHANGELOG.md

@@ -11,10 +11,6 @@
 
 * Add hybrid search documentation ([#457](https://github.com/googleapis/langchain-google-alloydb-pg-python/issues/457)) ([185b5b8](https://github.com/googleapis/langchain-google-alloydb-pg-python/commit/185b5b898c489e38b82c76462cad00ebfcd51414))
 
-### Code Refactoring
-
-* Refactor AlloyDBVectorStore and AlloyDBEngine to depend on PGVectorstore and PGEngine respectively ([#434](https://github.com/googleapis/langchain-google-alloydb-pg-python/issues/434)) ([2293bd7](https://github.com/googleapis/langchain-google-alloydb-pg-python/commit/2293bd76f294c3e62f08560311621f58a1628cdd))
-
 ## [0.12.0](https://github.com/googleapis/langchain-google-alloydb-pg-python/compare/v0.11.0...v0.12.0) (2025-06-02)