payload.py now uses async/await syntax

[eteamin]

issue #2343
however IOBasePayload and BytesPayload classes still use the old style async syntax for their write coroutines. Because changing their write coroutine to new syntax raises TypeError: object tuple can't be used in 'await' expression that I was unable to fix.

[codecov-io]

Codecov Report

Merging #2452 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2452      +/-   ##
==========================================
- Coverage   97.15%   97.15%   -0.01%     
==========================================
  Files          39       39              
  Lines        8124     8123       -1     
  Branches     1419     1419              
==========================================
- Hits         7893     7892       -1     
  Misses         99       99              
  Partials      132      132

Impacted Files	Coverage Δ
aiohttp/payload.py	98.85% <100%> (-0.01%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update fab1f23...24c9d9f. Read the comment docs.

[asvetlov]

Thanks!

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a [new issue] for related bugs.
If you feel like there's important points made in this discussion, please include those exceprts into that [new issue].
[new issue]: https://github.com/aio-libs/aiohttp/issues/new