Support Python 3.12

[ziw-liu]

Describe the bug
MONAI does not work with Python 3.12 since it uses the deprecated (and now removed) find_module API from importlib. See Python release note.

To Reproduce

Python 3.12.0 | packaged by conda-forge | (main, Oct  3 2023, 08:36:57) [Clang 15.0.7 ] on darwin
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>>> import monai
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/homebrew/Caskroom/miniforge/base/envs/p312/lib/python3.12/site-packages/monai/__init__.py", line 58, in <module>
    load_submodules(sys.modules[__name__], False, exclude_pattern=excludes)
  File "/opt/homebrew/Caskroom/miniforge/base/envs/p312/lib/python3.12/site-packages/monai/utils/module.py", line 212, in load_submodules
    importer.find_module(name).load_module(name)  # type: ignore
    ^^^^^^^^^^^^^^^^^^^^
AttributeError: 'FileFinder' object has no attribute 'find_module'

Expected behavior
This was previously put on hold in #7096 due to torch not supporting 3.12. Since torch now has Python 3.12 support in v2.2.1, MONAI should work as well.

[ziw-liu]

Already fixed in #7482. Looking forward to a new release!