Bump pytest from 5.4.3 to 6.0.1 (#59)

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-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

requirements.dev.txt

 flake8==3.8.3
 pylint==2.6.0
-pytest==5.4.3
+pytest==6.0.1
 pytest-watch==4.2.0