Faulty imports of packaging in version comparison logic

[nkaenzig]

Describe the bug
Wrong import statements in the functions version_leq and version_geq within monai.utils.module:

MONAI/monai/utils/module.py

Line 543 in 0a85eed

pkging, has_ver = optional_import("packaging.Version")

MONAI/monai/utils/module.py

Line 570 in 0a85eed

pkging, has_ver = optional_import("packaging.Version")

The Version class is exposed by the packaging.version submodule, therefore pkging, has_ver = optional_import("packaging.Version") always returns has_ver=False.

To Reproduce
Executing import packaging.Version in a python shell or script yields this error:

ModuleNotFoundError: No module named 'packaging.Version'

This issue currently doesn't surface because version_leq and version_geq both implement a fallback logic which is used when the import of packaging fails. However, I've observed more hidden consequences of this as described in #8348.

Expected behavior
Use packaging.version.Version for version comparisons, not the fallback after a failed import.

Environment

Ensuring you use the relevant python executable, please paste the output of:

================================
Printing MONAI config...
================================
MONAI version: 1.4.0
Numpy version: 1.26.4
Pytorch version: 2.5.1
MONAI flags: HAS_EXT = False, USE_COMPILED = False, USE_META_DICT = False
MONAI rev id: 46a5272196a6c2590ca2589029eed8e4d56ff008
MONAI __file__: /Users/<username>/workspace/kaiko-eng-worktrees/kaiko-eng/dist/export/python/virtualenvs/python-default/3.11.10/lib/python3.11/site-packages/monai/__init__.py

Optional dependencies:
Pytorch Ignite version: NOT INSTALLED or UNKNOWN VERSION.
ITK version: NOT INSTALLED or UNKNOWN VERSION.
Nibabel version: 4.0.2
scikit-image version: 0.24.0
scipy version: 1.14.1
Pillow version: 10.4.0
Tensorboard version: 2.18.0
gdown version: 5.2.0
TorchVision version: 0.20.1
tqdm version: 4.66.6
lmdb version: NOT INSTALLED or UNKNOWN VERSION.
psutil version: 6.1.0
pandas version: 2.1.4
einops version: 0.8.0
transformers version: 4.48.1
mlflow version: NOT INSTALLED or UNKNOWN VERSION.
pynrrd version: NOT INSTALLED or UNKNOWN VERSION.
clearml version: NOT INSTALLED or UNKNOWN VERSION.

For details about installing the optional dependencies, please visit:
    https://docs.monai.io/en/latest/installation.html#installing-the-recommended-dependencies


================================
Printing system config...
================================
System: Darwin
Mac version: 15.3.1
Platform: macOS-15.3.1-arm64-arm-64bit
Processor: arm
Machine: arm64
Python version: 3.11.10
Process name: python3.11
Command: ['python', '-c', 'import monai; monai.config.print_debug_info()']
Open files: []
Num physical CPUs: 10
Num logical CPUs: 10
Num usable CPUs: UNKNOWN for given OS
CPU usage (%): [47.4, 44.1, 61.7, 49.2, 40.5, 25.0, 26.1, 13.3, 8.1, 7.2]
CPU freq. (MHz): 3228
Load avg. in last 1, 5, 15 mins (%): [29.6, 26.7, 32.7]
Disk usage (%): 76.4
Avg. sensor temp. (Celsius): UNKNOWN for given OS
Total physical memory (GB): 64.0
Available memory (GB): 49.6
Used memory (GB): 12.3

================================
Printing GPU config...
================================
Num GPUs: 0
Has CUDA: False
cuDNN enabled: False
NVIDIA_TF32_OVERRIDE: None
TORCH_ALLOW_TF32_CUBLAS_OVERRIDE: None```