build: drop py38 (#263)

* build: drop py38

* bump min typing ext

* ignore cleanup warning from pyside6

* change minreq

* bump min

* fix for pint again

tests/zz_test_sliders/test_labeled_slider.py

@@ -1,4 +1,5 @@
-from typing import Any, Iterable
+from collections.abc import Iterable
+from typing import Any
 from unittest.mock import Mock
 
 import pytest

tests/zz_test_sliders/test_range_slider.py

@@ -1,6 +1,7 @@
 import math
+from collections.abc import Iterable
 from itertools import product
-from typing import Any, Iterable
+from typing import Any
 from unittest.mock import Mock
 
 import pytest