Update constants.py

Replace from numpy.asscalar to item() because numpy.asscalar causes FutureWarning.
Deprecated since numpy version 1.16: Deprecated, use numpy.ndarray.item() instead.

src/wrf/constants.py

@@ -16,7 +16,7 @@ class Constants(object):
 
 
 for key, val in viewitems(wrf_constants.__dict__):
-    setattr(Constants, key.upper(), np.asscalar(val))
+    setattr(Constants, key.upper(), val.item())
 
 OMP_SCHED_STATIC = omp_constants.fomp_sched_static
 OMP_SCHED_DYNAMIC = omp_constants.fomp_sched_dynamic