update argument usage

Author: emorway-usgs

autotest/test_gwe_drycell_cnd3.py

@@ -342,8 +342,8 @@ def add_gwe_model(sim, gwename):
         heat_capacity_water=cpw,
         density_water=rhow,
         latent_heat_vaporization=lhv,
-        cps=cps,
-        rhos=rhos,
+        heat_capacity_solid=cps,
+        density_solid=rhos,
         pname="EST",
         filename="{}.est".format(gwename),
     )