Switch from asyncio.iscoroutinefunction to inspect.

[frenzymadness]

The former causes: DeprecationWarning:
'asyncio.iscoroutinefunction' is deprecated and slated for removal in Python 3.16; use inspect.iscoroutinefunction() instead.

Fixes: #635

What do these changes do?

See the description in the commit message.

Are there changes in behavior for the user?

No

Related issue number

#635

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes

[Dreamsorcerer]

3.14 is still failing due to the same function call happening in pytest-asyncio.
Older versions are failing because the inspect function doesn't seem to behave the same (hopefully only on older releases...).

[frenzymadness]

I've implemented it in a way that older Pythons use the old way. pytest-asyncio is already fixed in the latest version: pytest-dev/pytest-asyncio@d043698 but I'm afraid it will cause the same issue for older Python as we saw here. Let's see what the tests tell us.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.00%. Comparing base (f60bf71) to head (44b0934).
Report is 101 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #637      +/-   ##
==========================================
+ Coverage   96.88%   97.00%   +0.11%     
==========================================
  Files          12       12              
  Lines         770      800      +30     
  Branches       91       41      -50     
==========================================
+ Hits          746      776      +30     
  Misses         22       22              
  Partials        2        2              

Flag	Coverage Δ
unit	95.62% <60.00%> (-1.13%)	⬇️

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[Dreamsorcerer]

Ah, Dependabot got stuck from 3.8 still being in the tests. Let me clear the Dependabot PRs quickly, which will get us an updated pytest-asyncio.

[Dreamsorcerer]

Looks like pytest-asyncio still needs some updates. Now it's DeprecationWarning: 'asyncio.get_event_loop_policy' is deprecated and slated for removal in Python 3.16.

[frenzymadness]

Reported: pytest-dev/pytest-asyncio#1049

[Dreamsorcerer]

Doesn't look like it'll be fixed for a while, so we should probably ignore the warning in pytest-asyncio.
Should be able to add an ignore rule to the config, similar to https://github.com/aio-libs/aiohttp/blob/b1fd3463f1d47919235f86d01e4cda3822450868/setup.cfg#L158

[Dreamsorcerer]

That's pytest-asyncio ignored, but still get 4 failures as it seems that the inspect function is still not equivalent of the asyncio one...

[Dreamsorcerer]

That's actually one more failure than we saw on older releases, suggesting the inspect function is actually less compatible in 3.14 than previous releases.