Use fixed length mask instead of dynamic length (#635)

pyrogram/types/object.py

@@ -56,7 +56,7 @@ class Object(metaclass=Meta):
             "_": obj.__class__.__name__,
             **{
                 attr: (
-                    "*" * len(getattr(obj, attr))
+                    "*" * 9
                     if attr == "phone_number" else
                     str(datetime.fromtimestamp(getattr(obj, attr)))
                     if attr.endswith("date") else