replace deprecated asyncio.iscoroutinefunction with inspect.iscoroutinefunction

[kumaraditya303]

Describe the bug

Python 3.14 deprecates asyncio.iscoroutinefunction in favor of inspect.iscoroutinefunction and aiohttp at some places uses the deprecated name so it should be changed to newer inspect.iscoroutinefunction.

To Reproduce

Run aiohttp tests on 3.14 to see the warnings.

Expected behavior

No warnings reported

Logs/tracebacks

NA

Python Version

$ python --version
Python 3.14.0a5+

aiohttp Version

$ python -m pip show aiohttp

multidict Version

$ python -m pip show multidict

propcache Version

$ python -m pip show propcache

yarl Version

$ python -m pip show yarl

OS

Linux

Related component

Client

Additional context

No response

Code of Conduct

• I agree to follow the aio-libs Code of Conduct

[asvetlov]

Thank you for raising the issue!

[Dreamsorcerer]

Note that those functions are not equivalent, so there may be some issues migrating.
See the attempt on async-lru already: aio-libs/async-lru#637

[Dreamsorcerer]

I've not investigated enough to figure out if that's deliberate or a CPython bug that should be fixed..

[kumaraditya303]

I looked at the linked aio-libs/async-lru#637, the fix for that is to call inspect.markcoroutinefunction on the object as that is now the official and supported way to mark such async functions, previously it required a private marker _is_coroutine.

https://github.com/aio-libs/async-lru/blob/284f36c24c5ed0873a72115a1ae88d6d89397da2/async_lru/__init__.py#L4