We officialy no longer support python < 3.9 as of D15373, but this fix is a low hanging fruit to allow non-python devs to keep running arc lint without updating python for a little while longer.

See https://docs.python.org/3/library/re.html#re.Match

Changed in version 3.9: re.Match supports [] to indicate a Unicode (str) or bytes match. See Generic Alias Type.