chore(deps): bump pytest from 3.0.6 to 5.2.1

Bumps [pytest](https://github.com/pytest-dev/pytest) from 3.0.6 to 5.2.1.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@3.0.6...5.2.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

test-requirements.txt

@@ -1,7 +1,7 @@
 -r requirements.txt
 coveralls
 mock
-pytest==3.0.6
+pytest==5.2.1
 pytest-cov==2.5.1
 pytest-flask==0.8.1
 PyYAML==5.1