Test failures with Python 3.12

[fabaff]

Describe the bug
Tests are failing on Python 3.12.

AttributeError: module 'importlib.abc' has no attribute 'Finder'

Expected behavior
What you expected to happen (please include a reference to the DICOM standard if relevant).

Steps To Reproduce
Run tests with pytest 8 and Python 3.12

============================= test session starts ==============================
platform linux -- Python 3.12.2, pytest-8.0.2, pluggy-1.4.0
rootdir: /build/source
plugins: pyfakefs-5.3.5
collected 2629 items / 2 errors / 502 deselected / 2127 selected               

==================================== ERRORS ====================================
_______________ ERROR collecting pynetdicom/tests/test_assoc.py ________________
pynetdicom/tests/test_assoc.py:69: in <module>
    from .hide_modules import hide_modules
pynetdicom/tests/hide_modules.py:33: in <module>
    _ModuleHiderBase = getattr(importlib.abc, "MetaPathFinder", importlib.abc.Finder)
/nix/store/fmwqa8nvva4sh18bqayzrilrzxq9fm0f-python3-3.12.2/lib/python3.12/importlib/abc.py:38: in __getattr__
    raise AttributeError(f'module {__name__!r} has no attribute {name!r}')
E   AttributeError: module 'importlib.abc' has no attribute 'Finder'
_____________ ERROR collecting pynetdicom/tests/test_transport.py ______________
pynetdicom/tests/test_transport.py:34: in <module>
    from .hide_modules import hide_modules
pynetdicom/tests/hide_modules.py:33: in <module>
    _ModuleHiderBase = getattr(importlib.abc, "MetaPathFinder", importlib.abc.Finder)
/nix/store/fmwqa8nvva4sh18bqayzrilrzxq9fm0f-python3-3.12.2/lib/python3.12/importlib/abc.py:38: in __getattr__
    raise AttributeError(f'module {__name__!r} has no attribute {name!r}')
E   AttributeError: module 'importlib.abc' has no attribute 'Finder'
=========================== short test summary info ============================
ERROR pynetdicom/tests/test_assoc.py - AttributeError: module 'importlib.abc' has no attribute 'Finder'
ERROR pynetdicom/tests/test_transport.py - AttributeError: module 'importlib.abc' has no attribute 'Finder'
!!!!!!!!!!!!!!!!!!! Interrupted: 2 errors during collection !!!!!!!!!!!!!!!!!!!!
====================== 502 deselected, 2 errors in 5.23s =======================

Your environment
n/a

[mrbean-bremen]

Duplicate of #851, needs a new release.