Update the changelog

Author: HaystackBot

integrations/pgvector/CHANGELOG.md

@@ -1,5 +1,14 @@
 # Changelog
 
+## [integrations/pgvector-v6.4.1] - 2026-07-23
+
+### 🐛 Bug Fixes
+
+- *(pgvector)* Parenthesize `not in` clause so it does not escape an AND filter (#3586)
+- `PGVectorDocumentStore` match `search_term` against metadata field value, not content (#3648)
+- Fix (pgvector): fix error messages to say pgvector instead of pinecone (#3654)
+
+
 ## [integrations/pgvector-v6.4.0] - 2026-07-23
 
 ### 🚀 Features