sanic-openapi: [Bug] TypeError: Object of type Spec is not JSON serializable

Description Trying to reproduce simple example with Getting Started code: https://sanic-openapi.readthedocs.io/en/latest/ When opens swager page see an error: Failed to load API definition. With previous version sanic-openapi 0.6.0 everithing works fine.

Screenshot

To Reproduce

from sanic import Sanic
from sanic.response import json
from sanic_openapi import swagger_blueprint

app = Sanic()
app.blueprint(swagger_blueprint)


@app.route("/")
async def test(request):
    return json({"hello": "world"})

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=8000)

Environment (please complete the following information):

• OS: Windows 10 x64
• Python: 3.7
• Browser: chrome 79.0.3948.88
• sanic-openapi: 0.6.1
• sanic: 19.12.2

Additional context

Traceback (most recent call last): File “C:\Users\user.virtualenvs\bbscreener\lib\site-packages\sanic\app.py”, line 974, in handle_request response = handler(request, *args, **kwargs) File “C:\Users\user.virtualenvs\bbscreener\lib\site-packages\sanic_openapi\swagger.py”, line 263, in spec return json(swagger_blueprint.spec) File “C:\Users\user.virtualenvs\bbscreener\lib\site-packages\sanic\response.py”, line 234, in json dumps(body, **kwargs), File "C:\Users\user\AppData\Local\Programs\Python\Python37\lib\json_init.py", line 238, in dumps **kw).encode(obj) File “C:\Users\user\AppData\Local\Programs\Python\Python37\lib\json\encoder.py”, line 199, in encode chunks = self.iterencode(o, _one_shot=True) File “C:\Users\user\AppData\Local\Programs\Python\Python37\lib\json\encoder.py”, line 257, in iterencode return _iterencode(o, 0) File “C:\Users\user\AppData\Local\Programs\Python\Python37\lib\json\encoder.py”, line 179, in default raise TypeError(f’Object of type {o.class.name} ’ TypeError: Object of type Spec is not JSON serializable