Bump pytest from 5.4.3 to 6.0.1

Bumps [pytest](https://github.com/pytest-dev/pytest) from 5.4.3 to 6.0.1.
- [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/5.4.3...6.0.1)

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

requirements-dev.txt

@@ -8,7 +8,7 @@ flake8==3.8.3
 flake8-type-annotations==0.1.0
 flake8-tidy-imports==4.1.0
 mypy==0.782
-pytest==5.4.3
+pytest==6.0.1
 pytest-asyncio==0.14.0
 pytest-cov==2.10.0
 pytest-mock==3.2.0