Add a check for python version in parallel to environment marker

[asvetlov]

If people install aiohttp on old non-supported Python the interpreter is very likely also has outdated setuptools without environment markers support.

The change will raise an exception on installation stage for such outdated systems.

[codecov-io]

Codecov Report

Merging #2813 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2813   +/-   ##
=======================================
  Coverage   97.99%   97.99%           
=======================================
  Files          39       39           
  Lines        7379     7379           
  Branches     1296     1296           
=======================================
  Hits         7231     7231           
  Misses         47       47           
  Partials      101      101

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[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