Bump pytest from 5.3.4 to 5.3.5 (#19)

Bumps [pytest](https://github.com/pytest-dev/pytest) from 5.3.4 to 5.3.5.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@5.3.4...5.3.5)

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