Update changelog for integrations/google_genai (#2065)

Co-authored-by: anakin87 <44616784+anakin87@users.noreply.github.com>

Author: HaystackBot

integrations/google_genai/CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## [integrations/google_genai-v1.3.0] - 2025-07-07
+
+### 🚀 Features
+
+- Google GenAI - add support for Vertex API (#2058)
+
+
 ## [integrations/google_genai-v1.2.0] - 2025-06-27
 
 ### 🐛 Bug Fixes