The asyncio `loop` parameter has been deprecated since Python 3.8
and is removed in Python 3.10. This deprecates use of the loop
parameter in aioitertools, and the parameters will be removed
with or after the release of aioitertools v0.11.0.
Adds a decorator `deprecated_wait_param()` that emits deprecation
warnings if the decorated functions are passed the `loop` kwarg.
Adds `@deprecated_wait_param` decorator to `as_completed()`,
`gather()`, and `gather_iter()` functions. The `loop` parameter
is no longer used, even if passed, so that aioitertools will work
on Python 3.10 runtimes.
Fixes#84
John Reese