fix: reverse change on order of operations

Defer to future investigation in #30 if we want to change these.

pyDeltaRCM/sed_tools.py

@@ -36,10 +36,10 @@ def sed_route(self):
 
         self.sand_route()
 
-        self.topo_diffusion()
-
         self.mud_route()
 
+        self.topo_diffusion()
+
     def deposit(self, Vp_dep, px, py):
         """deposit sand or mud"""