Pin the versions in requirements-dev.txt

[Mariatta]

Set pytest-aiohttp to v 0.1.3
Set pytest-asyncio to v 0.5.0
Set pytest to v 3.0.7

I tried running the tests locally last night and they failed due to recent updates in pytest-asyncio.

The tests passed again after setting pytest-asyncio to version 0.5.0
Per @brettcannon's suggestion, also set the version of pytest-aiohttp.

Edit: A lot of warnings were generated when using pytest 3.1.0. (travis log) Setting it the version to 3.0.7

[codecov]

Codecov Report

Merging #16 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master    #16   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           6      6           
  Lines         267    267           
  Branches        9      9           
=====================================
  Hits          267    267

---

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 17e5526...1153e05. Read the comment docs.

[Mariatta]

Hm, tests are passing now, but lots of warnings are being generated (see travis log)

[brettcannon]

"testing now" where? On master or in this PR?

[Mariatta]

Sorry, I don't understand your question..

The tests are failing when using requirements-dev.txt on master branch.
They pass again when using the versions specified in this PR.

[brettcannon]

Right, but you mentioned "lots of warnings are being generated" and I checked Travis for this PR and I didn't see any warnings, so I don't know what warnings you're referring to.

[Mariatta]

Ah yes, the warnings were here: https://travis-ci.org/python/bedevere/builds/237239682
The commit for that is: eb7c3f5

Setting pytest to 3.0.7 cleared the warnings for this PR.

[Mariatta]

The said warnings will be cleared in newer version of pytest-asyncio it seems (unreleased)
Thanks to another Python core developer pytest-dev/pytest-asyncio#51 :)

[brettcannon]

I tweaked the pins to allow for bugfix updates without having to explicitly update the dependencies.

Thanks for fixing this!