Bump pytest from 5.4.3 to 6.1.0

Bumps [pytest](https://github.com/pytest-dev/pytest) from 5.4.3 to 6.1.0.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@5.4.3...6.1.0)

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

requirements-dev.txt

@@ -2,7 +2,7 @@ black==20.8b1
 coveralls==2.1.2
 ddt==1.4.1
 flake8-import-order==0.18.1
-pytest==5.4.3
+pytest==6.1.0
 pytest-cov==2.10.1
 pytest-json==0.4.0
 pytest-pythonpath==0.7.3