Update pytest-mypy to 0.10.3

[pyup-bot]

This PR updates pytest-mypy from 0.3.2 to 0.10.3.

The bot wasn't able to find a changelog for this release. Got an idea?

Links

• PyPI: https://pypi.org/project/pytest-mypy
• Repo: https://github.com/dbader/pytest-mypy