Update pytest-mock from 1.6.2 to 1.6.3 (#5)

Author: pyup-bot

tests/requirements.txt

@@ -8,7 +8,7 @@ Pygments==2.2.0
 pytest==3.2.2
 pytest-cov==2.5.1
 pytest-isort==0.1.0
-pytest-mock==1.6.2
+pytest-mock==1.6.3
 pytest-sugar==0.9.0
 pytest-toolbox==0.2
 numpy  # pyup: ignore