fixup! fix: Ensure group tasks are deeply deserialised

celery/canvas.py

@@ -1028,7 +1028,7 @@ class group(Signature):
 
     @classmethod
     def from_dict(cls, d, app=None):
-        tasks = [maybe_signature(task) for task in d["kwargs"]["tasks"]]
+        tasks = [maybe_signature(task, app=app) for task in d["kwargs"]["tasks"]]
         return _upgrade(
             d, group(tasks, app=app, **d['options']),
         )