core: migrate code to benefit from 3.9 stuff (#401)

for now keeping ruff on 3.8 target version, need to sort out modules as well

my/core/_deprecated/kompress.py

@@ -1,16 +1,17 @@
 """
 Various helpers for compression
 """
+
 # fmt: off
 from __future__ import annotations
 
 import io
 import pathlib
-import sys
+from collections.abc import Iterator, Sequence
 from datetime import datetime
 from functools import total_ordering
 from pathlib import Path
-from typing import IO, Any, Iterator, Sequence, Union
+from typing import IO, Any, Union
 
 PathIsh = Union[Path, str]