Update CHANGELOG.md

Author: dishaprakash

CHANGELOG.md

@@ -1,6 +1,6 @@
 # Changelog
 
-## [0.13.0](https://github.com/googleapis/langchain-google-cloud-sql-pg-python/compare/v0.14.1...v0.13.0) (2025-08-20)
+## [0.15.0](https://github.com/googleapis/langchain-google-cloud-sql-pg-python/compare/v0.14.1...v0.15.0) (2025-08-20)
 
 
 ### ⚠ BREAKING CHANGES