up to python 3.10

[dpineiden]

To use with python 3.10 some little changes are necesary.

Callable uses collections.abc

• ast collections Callable

Drop loop arg

• asyncio_net open_connection
• wait_for

[srh]

Going to close, because, first, this only drops one of the loop parameters (there are a couple more that need to be dropped) and second, the change to collections.abc.Callable should be unnecessary as we rename collections.abc while importing.

And PR #296 removes all the loop params that need it.

Also, the collections.abc change would break Python <3.3, which we don't want to deliberately break unless it's basically necessary.