Remove builtins imports

This module is not intended to be used directly in most cases, per:
https://docs.python.org/3/library/builtins.html

None of our usages warrant the explicit import. We also avoid some
confusion as folks dig to see what we are doing to require
importing builtins directly.

evennia/server/sessionhandler.py

@@ -13,7 +13,6 @@ There are two similar but separate stores of sessions:
 
 """
 import time
-from builtins import object
 
 from django.conf import settings
 from evennia.commands.cmdhandler import CMD_LOGINSTART