Use assert_never from typing_extensions not typing.

Author: nathanjmcdougall

pins/drivers.py

@@ -4,7 +4,8 @@
 from .meta import Meta
 from .errors import PinsInsecureReadError
 
-from typing import Literal, Sequence, assert_never
+from typing import Literal, Sequence
+from typing_extensions import assert_never
 
 # TODO: move IFileSystem out of boards, to fix circular import
 # from .boards import IFileSystem