Update outputdt for test

Author: VeckoTheGecko

tests/v4/test_advection.py

@@ -65,7 +65,7 @@ def test_advection_zonal_with_particlefile(tmp_store):
     fieldset = FieldSet([U, V, UV])
 
     pset = ParticleSet(fieldset, lon=np.zeros(npart) + 20.0, lat=np.linspace(0, 80, npart))
-    pfile = ParticleFile(tmp_store, outputdt=np.timedelta64(15, "m"))
+    pfile = ParticleFile(tmp_store, outputdt=np.timedelta64(30, "m"))
     pset.execute(AdvectionRK4, runtime=np.timedelta64(2, "h"), dt=np.timedelta64(15, "m"), output_file=pfile)
 
     assert (np.diff(pset.lon) < 1.0e-4).all()