Import Iterable and Iterator depending on Python version

libkeyringctl/{keyring,sequoia,util}.py:
As Iterable and Iterator are only used for type hints, switch to using
typing.{Iterable,Iterator} instead of
collections.abc.{Iterable,Iterator} for Python < 3.9.0, as older Python
interpreters will otherwise raise TypeError.

libkeyringctl/keyring.py

 # SPDX-License-Identifier: GPL-3.0-or-later
 
 from collections import defaultdict
-from collections.abc import Iterable
 from itertools import chain
 from logging import debug
 from logging import error
 from pathlib import Path
+from platform import python_version_tuple
 from re import match
 from shutil import copytree
 from tempfile import NamedTemporaryFile
 from tempfile import mkdtemp
 from typing import Dict
+
+# NOTE: remove after python 3.8.x is no longer supported upstream
+if int(python_version_tuple()[1]) < 9:  # pragma: no cover
+    from typing import Iterable
+else:
+    from collections.abc import Iterable
 from typing import List
 from typing import Optional
 from typing import Set

libkeyringctl/sequoia.py

 # SPDX-License-Identifier: GPL-3.0-or-later
 
-from collections.abc import Iterable
 from datetime import datetime
 from functools import reduce
 from pathlib import Path
+from platform import python_version_tuple
 from re import sub
 from tempfile import mkdtemp
 from typing import Dict
+
+# NOTE: remove after python 3.8.x is no longer supported upstream
+if int(python_version_tuple()[1]) < 9:  # pragma: no cover
+    from typing import Iterable
+else:
+    from collections.abc import Iterable
 from typing import List
 from typing import Optional
 

libkeyringctl/util.py

 # SPDX-License-Identifier: GPL-3.0-or-later
-from collections.abc import Iterable
-from collections.abc import Iterator
 from contextlib import contextmanager
 from hashlib import sha256
 from os import chdir
 from os import environ
 from os import getcwd
 from pathlib import Path
+from platform import python_version_tuple
 from re import escape
 from re import split
 from re import sub
@@ -22,6 +21,14 @@ from traceback import print_stack
 from typing import IO
 from typing import AnyStr
 from typing import Dict
+
+# NOTE: remove after python 3.8.x is no longer supported upstream
+if int(python_version_tuple()[1]) < 9:  # pragma: no cover
+    from typing import Iterable
+    from typing import Iterator
+else:
+    from collections.abc import Iterable
+    from collections.abc import Iterator
 from typing import List
 from typing import Optional
 from typing import Set