aiohttp: RuntimeWarning: coroutine 'noop' was never awaited (4.0.0a1-py3.6 / 3.6.2-py3.8)

Description

When using the lastest slackclient, which pulls in the aiohttp in setup.py with

install_requires=["aiohttp>3.5.2"],

Results in aiohttp version 4.0.0.a1. When using this version I noticed the following output when invoking the WebClient api calls, for example chat_postMessage

/Users/jeremy/venv/lib/python3.6/site-packages/aiohttp-4.0.0a1-py3.6-macosx-10.14-x86_64.egg/aiohttp/client.py:977: RuntimeWarning: coroutine 'noop' was never awaited

If I downgraded the version of aiohttp to < 4.0, I obtain version 3.6.2 . I no longer see the above issue when using this version.

I don't know if this issue rises to the level of a "bug" per-se since I don't see any issue in my app; and I believe this might just be a warning. Unsure. I did find this one related bug:
https://github.com/aio-libs/aiohttp/issues/4282.

What type of issue is this? (place an x in one of the [ ])

• bug
• enhancement (feature request)
• question
• documentation related
• testing related
• discussion

Requirements (place an x in each of the [ ])

• I've read and understood the Contributing guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've searched for any related issues and avoided creating a duplicate issue.

Bug Report

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Reproducible in:

slackclient version: 2.0

python version: 3.6.8

OS version(s): MacOS Mojave

Steps to reproduce:

1. Use aiohttp >= 4.0
2. Execute any WebClient api call
3. observe the RuntimeWarning as noted
4. Downgrade aiohttp < 4.0
5. Re-execute any WEbClient api call
6. Do not observe the RuntimeWarning.

Expected result:

Ideally be able to use the latest aiohttp library and not see this RuntimeWarning

Actual result:

Currently observing RuntimeWarning with aiohttp > 4.0

Attachments:

Logs, screenshots, screencast, sample project, funny gif, etc.

Start with setup.py and the WebClient API call path described in the report, then reproduce the warning using aiohttp >= 4.0 with Python 3.6. Compare the behavior against aiohttp 3.6.2 and determine whether the warning comes from the SDK or its dependency. Done means the affected WebClient calls no longer emit the reported RuntimeWarning with the supported dependency range.