Add parametrize_device_name to setup.cfg

[emcastillo]

This was preventing ChainerX from running with newer pytest versions

E   pytest.PytestUnknownMarkWarning: Unknown pytest.mark.parametrize_device_name - is this a typo?  You can register custom marks to avoid this warning - for details, see https://docs.pytest.org/en/latest/mark.html

[toslunar]

LGTM

The cause is the conflict between #7988 and #8112.

[toslunar]

Jenkins & flexCI, test this please.

[chainer-ci]

Jenkins CI test (for commit 6a0e179, target branch master) succeeded!