Updating to ensure mapping is pulled from repo (#82)

Author: kronos30

tailor_distro/create_recipes.py

@@ -16,7 +16,7 @@
 def nested_update(d, u):
     d = deepcopy(d)
     for k, v in u.items():
-        if isinstance(v, collections.Mapping):
+        if isinstance(v, collections.abc.Mapping):
             d[k] = nested_update(d.get(k, {}), v)
         else:
             d[k] = v