Disabled debug when running the tests
    
    This is required for flask 1.0 due to:
    https://github.com/pallets/flask/issues/2735
    Fixed in 1.0.1 but 1.0.1 isn't out yet so... :)
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr></pingou@pingoured.fr>