Scheduled weekly dependency update for week 27 (#314)

* Update pytest from 3.6.1 to 3.6.3

* Update docker from 3.3.0 to 3.4.1

* Update sqlalchemy from 1.2.8 to 1.2.9

Author: pyup.io bot

requirements-dev.txt

@@ -2,11 +2,11 @@ coverage==4.5.1
 flake8==3.5.0
 ipdb==0.11
 ipython==6.4.0
-pytest==3.6.1
+pytest==3.6.3
 pytest-cov==2.5.1
 pytest-sugar==0.9.1
 PyMySQL>=0.9,<=0.9.2
-docker==3.3.0
+docker==3.4.1
 sphinx==1.7.5
 sphinxcontrib-asyncio==0.2.0
-sqlalchemy==1.2.8
+sqlalchemy==1.2.9