manage.py: Don't use Flask-Script with Flask 2.0.0
Since version 2.0.0, Flask-Script is not provided anymore and the Database management must use the Flask CLI instead, see [1].
This patch makes the run-qa-report script use the CLI and manage.py is adapted to be used by the CLI.
[1] https://blog.miguelgrinberg.com/post/migrating-from-flask-script-to-the-new-flask-cli