Fix errors reported by mypy

Signed-off-by: Jan Lindemann <jan@janware.com>

tools/python/jwutils/Cmd.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 
 from __future__ import annotations
-from typing import List, Type, Union, TypeVar
+from typing import Optional, List, Type, Union, TypeVar
 import inspect, sys, re, abc, argparse
 from argparse import ArgumentParser, _SubParsersAction
 
@@ -17,6 +17,7 @@ class Cmd(abc.ABC): # export
         pass
 
     def __init__(self, name: str, help: str) -> None:
+        from . import Cmds
         self.name = name
         self.help = help
         self.parent = None