Scheduled weekly dependency update for week 38 (#320)

* Update attrs from 18.1.0 to 18.2.0

* Update sphinx from 1.7.6 to 1.8.1

* Update cryptography from 2.3 to 2.3.1

* Update pytest from 3.6.4 to 3.8.1

* Update pytest-cov from 2.5.1 to 2.6.0

* Update aiohttp from 3.3.2 to 3.4.4

* Update multidict from 4.3.0 to 4.4.2

Author: pyup.io bot

requirements-dev.txt

@@ -1,19 +1,19 @@
-attrs==18.1.0
+attrs==18.2.0
 flake8==3.5.0
-sphinx==1.7.6
+sphinx==1.8.1
 pep257==0.7.0
 -e .
 aioredis==1.1.0
-cryptography==2.3
+cryptography==2.3.1
 docker==3.4.1
 pynacl==1.2.1
-pytest==3.6.4
+pytest==3.8.1
 pytest-aiohttp==0.3.0
-pytest-cov==2.5.1
+pytest-cov==2.6.0
 pytest-mock==1.10.0
 pytest-sugar==0.9.1
-aiohttp==3.3.2
-multidict==4.3.0
+aiohttp==3.4.4
+multidict==4.4.2
 chardet==3.0.4
 yarl==1.2.6
 aiomcache==0.6.0