Update pytest from 4.5.0 to 4.6.0

Author: pyup-bot

dev-requirements.txt

@@ -17,7 +17,7 @@ Pygments==2.4.2
 pylint==2.3.1  # Lint
 pyroma==2.4  # Packaging best practices checker
 pytest-cov==2.7.1  # Measure code coverage
-pytest==4.5.0  # Test runners
+pytest==4.6.0  # Test runners
 PyYAML==5.1
 Sphinx==2.0.1
 sphinx-autodoc-typehints==1.6.0