Remove support for python <3.11 (#1273)

Python 3.11 ships with latest Debian Bookworm. 
pypy is not that widely used with this library based on statistics. It could be added back when pypy supports python 3.11.

tests/fixtureinfo.py

@@ -4,8 +4,9 @@ import copy
 import glob
 import json
 import os
+from collections.abc import Iterable
 from pathlib import Path
-from typing import Iterable, NamedTuple
+from typing import NamedTuple
 
 import pytest