fix: Switch import location

In Python 3.9, `typing.Sequence` was deprecated in favor of
`collections.abc.Sequence` (see PEP 585).

reverse_argparse/reverse_argparse.py

@@ -15,7 +15,7 @@
 
 import re
 from argparse import SUPPRESS, Action, ArgumentParser, Namespace
-from typing import Sequence
+from collections.abc import Sequence
 
 
 SHORT_OPTION_LENGTH = 2