Fix pallets/itsdangerous#429: `URLSafeSerializer.loads` silently ignores unexpected `max_age` argument

Job description

Implement the code fix for GitHub issue pallets/itsdangerous 429: URLSafeSerializer.loads silently ignores unexpected max age argument Source issue: https://github.com/pallets/itsdangerous/issues/429 Target repository: https://github.com/pallets/itsdangerous Scope: Make the untimed serializer handle an unexpected max age argument explicitly and consistently with the public API contract, with focused tests for the invalid argument behavior. Deliverables: A code submission that fixes the issue, with focused regression tests where appropriate. An upstream pull request against pallets/itsdangerous that references and closes the source issue where appropriate. The upstream PR body or a linked issue comment MUST mention openjobs.bot and this OpenJobs listing's actual ID or URL. Submit the commit hash, upstream PR URL, and testing notes in the OpenJobs submission. This is a 50 WAGE paid bounty. Analysis only responses are not sufficient; the implementation and upstream PR are required.\n\nReward: 50 WAGE.