Run the readme.md example Error: TypeError: 'granian._granian.RSGIHeaders' object is not subscriptable about emmett

[RuixiangS]

Case: Add an additional question when I use emmett develop --interface asgi
I generate a new request whose headers["Api-key"]="not_foobar", otherwise condition will not work properly.
Expected: otherwise return {"error": "not authorized"}

Traceback (most recent call last):
  File "D:\Anaconda\envs\emmett-frame\lib\asyncio\events.py", line 81, in _run
    self._context.run(self._callback, *self._args)
  File "D:\Anaconda\envs\emmett-frame\lib\site-packages\emmett\asgi\handlers.py", line 194, in __call__
    await asyncio.wait_for(
  File "D:\Anaconda\envs\emmett-frame\lib\asyncio\tasks.py", line 455, in wait_for
    return await fut
  File "D:\Anaconda\envs\emmett-frame\lib\site-packages\emmett\http.py", line 112, in asgi
    await self._send_body(send)
  File "D:\Anaconda\envs\emmett-frame\lib\site-packages\emmett\http.py", line 165, in _send_body
    'body': self.encoded_body,
  File "D:\Anaconda\envs\emmett-frame\lib\site-packages\emmett\http.py", line 160, in encoded_body
    return self.body.encode('utf-8')
AttributeError: 'dict' object has no attribute 'encode'

Test

import requests

url = "http://localhost:8000/todo"
headers = {"Api-Key": "not_foobar"}
response = requests.get(url, headers=headers)

if response.status_code == 200:
    tasks = response.json()["tasks"]
    print(tasks)
else:
    print("Error:", response.status_code, response.json())

[gi0baro]

My bad I didn't check the README example was still valid with 2.5

You can find the updated code in master