www/py-flask-jwt-extended: Update to 4.3.1

Release 4.0.0 includes a lot of breaking changes, and will require some manual intervention to upgrade, see https://flask-jwt-extended.readthedocs.io/en/stable/v4_upgrade_guide/

Changelog: https://github.com/vimalloc/flask-jwt-extended/compare/3.25.0...4.3.1

PR: 254039