Bump pytest from 4.4.1 to 5.3.0

Bumps [pytest](https://github.com/pytest-dev/pytest) from 4.4.1 to 5.3.0.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@4.4.1...5.3.0)

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

requirements/tests.txt

@@ -4,7 +4,7 @@ mock==2.0.0
 pbr==5.1.3
 pluggy==0.12.0
 py==1.8.0
-pytest==4.4.1
+pytest==5.3.0
 pytest-cov==2.7.1
 six==1.12.0
 python-coveralls==2.9.2