Revert a change that would cause massive notebook problems.

src/sage/server/notebook/cell.py

@@ -39,7 +39,7 @@
 from   sage.misc.preparser import strip_string_literals
 
 
-class Cell_generic(object):
+class Cell_generic:
     def is_interactive_cell(self):
         """
         Returns True if this cell contains the use of interact either