feat: set default utc timezone for postgresql in DatabaseService (#8112)

Co-authored-by: tianzhipeng <tzpabc@gmail.com>

src/backend/base/langflow/services/database/service.py

@@ -156,7 +156,9 @@ class DatabaseService(Service):
                 "check_same_thread": False,
                 "timeout": settings.db_connect_timeout,
             }
-
+        # For PostgreSQL, set the timezone to UTC
+        if settings.database_url and settings.database_url.startswith(("postgresql", "postgres")):
+            return {"options": "-c timezone=utc"}
         return {}
 
     def on_connection(self, dbapi_connection, _connection_record) -> None: