Run test_particleset_interpolate_outside_domainedge with 2 day execution time

With the fence posting bugfix in place, the particleset execute call
updates the position once; previously, this happened twice (this was the
bug). This test failed because the particle didn't go out of bounds with
a single position update. Semantically, setting the runtime to 2 days,
achieved what was intended here (to get the particle out of bounds)

Author: fluidnumericsJoe

tests/test_particleset_execute.py

@@ -203,7 +203,7 @@ def SampleU(particles, fieldset):  # pragma: no cover
     pset = ParticleSet(fieldset, lon=fieldset.U.grid.lon[-1], lat=fieldset.U.grid.lat[-1] + dlat)
 
     with pytest.raises(FieldOutOfBoundError):
-        pset.execute(SampleU, runtime=np.timedelta64(1, "D"), dt=np.timedelta64(1, "D"))
+        pset.execute(SampleU, runtime=np.timedelta64(2, "D"), dt=np.timedelta64(1, "D"))
 
 
 @pytest.mark.parametrize(