Update pytest from 3.0.3 to 3.0.4 (#200)

requirements.txt

@@ -9,7 +9,7 @@ setuptools==28.7.1
 -e .[sa]
 sphinx==1.4.8
 tox==2.4.1
-pytest==3.0.3
+pytest==3.0.4
 pytest-cov==2.4.0
 pytest-sugar==0.7.1
 pytest-timeout==1.2.0