Merge pull request #246 from aio-libs/pyup-update-pytest-3.3.1-to-3.4.0

Update pytest to 3.4.0

Author: jettify

requirements-dev.txt

@@ -2,7 +2,7 @@ coverage==4.4.2
 flake8==3.4.1
 ipdb==0.10.2
 ipython==6.1.0
-pytest==3.3.1
+pytest==3.4.0
 pytest-cov==2.5.1
 pytest-sugar==0.9.0
 sphinx==1.6.5