Update aiohttp to 2.3.4

[pyup-bot]

There's a new version of aiohttp available.
You are currently using 2.3.3. I have updated it to 2.3.4

These links might come in handy: PyPI | Changelog | Repo

Changelog

2.3.4

==================

• Make request.app point to proper application instance when using nested
  applications (with middlewares). (2550)
• Change base class of ClientConnectorSSLError to ClientSSLError from
  ClientConnectorError. (2563)
• Return client connection back to free pool on error in connector.connect().
  (2567)

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖

[codecov]

Codecov Report

Merging #354 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master    #354   +/-   ##
======================================
  Coverage    97.4%   97.4%           
======================================
  Files          18      18           
  Lines         887     887           
======================================
  Hits          864     864           
  Misses         23      23

---

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 d6dc101...13a765b. Read the comment docs.

[coveralls]

Coverage remained the same at 97.407% when pulling 13a765b on pyup-update-aiohttp-2.3.3-to-2.3.4 into d6dc101 on master.

[pyup-bot]

Closing this in favor of #355