chore(deps-dev): update pytest requirement from ^4.0 to ^5.0

Updates the requirements on [pytest](https://github.com/pytest-dev/pytest) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@4.0.0...5.0.0)

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

Author: dependabot-preview[bot]

pyproject.toml

@@ -55,7 +55,7 @@ tomlkit = "^0.5.3"
 [tool.poetry.dev-dependencies]
 ipython = "^7.2"
 black = "^19.3b0"
-pytest = "^4.0"
+pytest = "^5.0"
 flake8 = "^3.6"
 pytest-cov = "^2.6"
 pytest-mock = "^1.10"