Test data repository markers
Created by: peterfpeterson
This moves the test selection for the builds to use a datarepo
pytest marker. Tests that are using the imars3d-data repository should be marked with
@pytest.mark.datarepo
Then the tests can be run with either python -m pytest -m datarepo
for things that require the data repository or python -m pytest -m "not datarepo"
for things that don't. A full list of available markers can be seen using python -m pytest --markers