Remove "convert_unicode"

[diogobaeder]

Hi,

The "convert_unicode" argument is being used in flask-sqlalchemy, however it's deprecated in SQLAlchemy:

SADeprecationWarning: The create_engine.convert_unicode parameter and corresponding dialect-level parameters are deprecated, and will be removed in a future release.  Modern DBAPIs support Python Unicode natively and this parameter is unnecessary.
    default.DefaultDialect.__init__(self, **kwargs)

So the options here should probably be an empty dict, right?: https://github.com/pallets/flask-sqlalchemy/blob/50944e77522d4aa005fc3c833b5a2042280686d3/flask_sqlalchemy/__init__.py#L558

Thanks,
Diogo

[rsyring]

Thanks for the report. This will be resolved in #684.

[diogobaeder]

Ah, cool, good to know! Thanks!

(Feel free to close the issue if it's not relevant anymore)