update extension name (#7359)

hi @rlancemartin ,

We had a new deployment and the `pg_extension` creation command was
updated from `CREATE EXTENSION pg_embedding` to `CREATE EXTENSION
embedding`.

https://github.com/neondatabase/neon/pull/4646

The extension not made public yet. No users will be affected by this.
Will be public next week.

Please let me know if you have any questions.

Thank you in advance 🙏

langchain/vectorstores/pgembedding.py

@@ -143,9 +143,7 @@ class PGEmbedding(VectorStore):
     def create_hnsw_extension(self) -> None:
         try:
             with Session(self._conn) as session:
-                statement = sqlalchemy.text(
-                    "CREATE EXTENSION IF NOT EXISTS pg_embedding"
-                )
+                statement = sqlalchemy.text("CREATE EXTENSION IF NOT EXISTS embedding")
                 session.execute(statement)
                 session.commit()
         except Exception as e: