Add support for Aiohttp 4.0

[sethmlarson]

Looks like Aiohttp 4.0 changes a few APIs, we should ensure we're compatible so when 3.6 is finally released our users can use it right away.

[Sparkycz]

Hey @sethmlarson,

Aiohttp version 3.7.x has been released with the incompatible commit aio-libs/aiohttp@e7e6c20#diff-b797dd8733928df191ba2061121ab8b69976c185fcbfad4534891d3252b9ac30R100

There is replace of the coroutine function noop by class and it causes raising of TypeError at https://github.com/elastic/elasticsearch-py-async/blob/master/elasticsearch_async/connection.py#L115
because noop is not already iterable.

ShortTerm fix might be downgrade of aiohttp in setup.py (aiohttp<3.7)
LongTerm fix might be

1. catching the TypeError in this library or
2. add function __iter__(...) to the noop class to get it iterable

I'm able to create the PRs but I'd like to agree on the right solution.

[sethmlarson]

@Sparkycz You point at the repository elasticsearch-py-async (elasticsearch-async on PyPI) and this is the repo elasticsearch-py (elasticsearch on PyPI). Has there been a mix-up here? Can you try aiohttp 3.7 after installing elasticsearch[async] as documented here?

[Sparkycz]

Yes, It works. Thank you.