Ignoring sgrid tests for now

As SGrid support will probably be removed in v4 anyways (see #1914)

Author: erikvansebille

tests/test_grids.py

@@ -455,7 +455,8 @@ def sampleVel(particle, fieldset, time):  # pragma: no cover
     assert (pset[0].meridional - 1) < 1e-6
 
 
-@pytest.mark.parametrize("vert_mode", ["zlev", "slev1", "slev2"])
+@pytest.mark.v4alpha
+@pytest.mark.parametrize("vert_mode", ["zlev"])  # , "slev1", "slev2"])  # v4 not supported?
 @pytest.mark.parametrize("time", [True, False])
 def test_cgrid_uniform_3dvel(vert_mode, time):
     lon = np.array([[0, 2], [0.4, 1.5]])