Add pytest-datafiles

[marcelotduarte]

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[conda-forge-webservices[bot]]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipes/pytest-datafiles) and found it was in an excellent condition.

[marcelotduarte]

I confirm that I'm willing to be listed as a maintainer.

@conda-forge-admin, please ping conda-forge/help-python Ready for review!

[conda-forge-webservices[bot]]

Hi! This is the friendly automated conda-forge-webservice.

I was asked to ping @conda-forge/help-python and so here I am doing that.