Merge pull request #206 from aio-libs/pyup-update-coverage-4.3.4-to-4.4.1

Update coverage to 4.4.1

Author: jettify

requirements-dev.txt

@@ -1,4 +1,4 @@
-coverage==4.3.4
+coverage==4.4.1
 flake8==3.4.1
 ipdb==0.10.2
 ipython==6.1.0