Bump pytest from 3.4.2 to 5.4.2

Bumps [pytest](https://github.com/pytest-dev/pytest) from 3.4.2 to 5.4.2.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/pytest-dev/pytest/compare/3.4.2...5.4.2)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements-tests.txt

 -r requirements.txt
 attrs==19.1.0
-pytest==3.4.2
+pytest==5.4.2
 pytest-cov==2.8.1
 mock==2.0.0
 flake8==3.5.0