Bump pytest from 5.2.4 to 5.3.0 in /{{cookiecutter.app_name}}

Bumps [pytest](https://github.com/pytest-dev/pytest) from 5.2.4 to 5.3.0.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/5.3.0/CHANGELOG.rst)
- [Commits](https://github.com/pytest-dev/pytest/compare/5.2.4...5.3.0

)

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