Changed dropped dictionary from empty to {'...': '...'}.

rollbar/lib/transforms/shortener.py

@@ -186,7 +186,7 @@ def _should_drop(self, val, key) -> bool:
     def default(self, o, key=None):
         if self._should_drop(o, key):
             if isinstance(o, (dict, Mapping)):
-                return dict()
+                return {'...': '...'}
             if isinstance(o, sequence_types):
                 return ['...']