Fix pytest deprecation warning
conftest uses the Function attribute of a pytest.Function object. Latest
pytest has deprecated the attribute:
_pytest.warning_types.RemovedInPytest4Warning: usage of Function.Function
is deprecated, please use pytest.Function instead
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Serhii Tsymbaliuk <stsymbal@redhat.com>