app.json_encoder usage is deprecated and will be removed in Flask 2.3.0

[djhoese]

See pallets/flask#4692

Running my tests I see these warnings:

../../../miniconda3/envs/rain_py311/lib/python3.11/site-packages/flask_json.py:547
  /home/davidh/miniconda3/envs/rain_py311/lib/python3.11/site-packages/flask_json.py:547: DeprecationWarning: 'app.json_encoder' is deprecated and will be removed in Flask 2.3. Customize 'app.json_provider_class' or 'app.json' instead.
    app.json_encoder = self._encoder_class

../../../miniconda3/envs/rain_py311/lib/python3.11/site-packages/flask_json.py:674
  /home/davidh/miniconda3/envs/rain_py311/lib/python3.11/site-packages/flask_json.py:674: DeprecationWarning: 'app.json_encoder' is deprecated and will be removed in Flask 2.3. Customize 'app.json_provider_class' or 'app.json' instead.
    self._app.json_encoder = JSONEncoderWithHook

[skozlovf]

@djhoese Yep, I plan to rework internals to switch to the new flask API.

[djhoese]

Sounds good. Thanks! I just wasn't sure and wanted to check.

[skozlovf]

Fixed in 0.4.0.