Python:latest in Docker build fails

[HankQuiter]

the docker build fails with the following error
AIOHTTP I think is the wrong version based on
aio-libs/aiohttp#4005

Successfully tagged blusky/pickleprick:latest
Traceback (most recent call last):
File "pickleprick.py", line 1, in
from aiohttp_session.cookie_storage import EncryptedCookieStorage
File "/usr/local/lib/python3.7/site-packages/aiohttp_session/init.py", line 9, in
from aiohttp import web
File "/usr/local/lib/python3.7/site-packages/aiohttp/init.py", line 6, in
from .client import * # noqa
File "/usr/local/lib/python3.7/site-packages/aiohttp/client.py", line 15, in
from . import connector as connector_mod
File "/usr/local/lib/python3.7/site-packages/aiohttp/connector.py", line 13, in
from . import hdrs, helpers
File "/usr/local/lib/python3.7/site-packages/aiohttp/helpers.py", line 30
ensure_future = asyncio.async
^
SyntaxError: invalid syntax

[HankQuiter]

I switched the line in requirments.txt to
aiohttp==3.5.4
that is instead of 2.2.5 and it built and ran - idk if the tutorial blog post stuff works yet but I'll try that another time

[HankQuiter]

The blog post tutorial here how to exploit this works with the above solution - switching the aiohttp to version 3.5.4