Fix update_query_string() returns new URL instance

This sqlalchemy.engine.url.URL method returns a new URL instance, and
doesn't update in place:
https://github.com/sqlalchemy/sqlalchemy/blob/fc2bcead435a9bf0a2de8e9b15a1bd835f9d7fe4/lib/sqlalchemy/engine/url.py#L360

src/tentaclio/clients/sqla_client.py

@@ -97,7 +97,7 @@ def _connect(self) -> Connection:
             database=self.database,
         )
         if self.url.query_string:
-            parsed_url.update_query_string(self.url.query_string)
+            parsed_url = parsed_url.update_query_string(self.url.query_string)
         if self.engine is None:
             self.engine = create_engine(
                 parsed_url,