[Fix] Replace deprecated pkg_resources with importlib

[MGAMZ]

This is a sub-PR of #1665

Brief

pkg_resources is no longer supported and is due to be completed abandoned in Nov. 2025. Replacing it with importlib. This causes many modifications in mmengine/utils/package_utils.py

PyTest

The test unit is modified to importlib: tests/test_utils/test_package_utils.py

=================================================== test session starts ===================================================
platform linux -- Python 3.13.9, pytest-8.4.1, pluggy-1.6.0 -- /home/mgam/miniforge3/envs/pt/bin/python3.13
cachedir: .pytest_cache
rootdir: /home/mgam/mgam_repos/mmengine
configfile: pytest.ini
plugins: anyio-4.9.0, hydra-core-1.3.2
collected 2 items                                                                                                         

tests/test_utils/test_package_utils.py::test_is_installed PASSED                                                    [ 50%]
tests/test_utils/test_package_utils.py::test_get_install_path PASSED                                                [100%]

==================================================== 2 passed in 0.19s ====================================================

[Copilot]

Pull Request Overview

This PR migrates from the deprecated pkg_resources to the modern importlib.metadata API, which is the recommended approach for package introspection in Python 3.8+. The deprecated pkg_resources module is scheduled for complete removal in November 2025.

Key Changes:

• Replaced pkg_resources imports with importlib.metadata throughout the codebase
• Updated exception handling to use PackageNotFoundError instead of DistributionNotFound
• Implemented version-specific logic to handle differences between Python 3.8 and 3.9+ APIs

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
mmengine/utils/package_utils.py	Core migration from pkg_resources to importlib.metadata for all package introspection functions
tests/test_utils/test_package_utils.py	Updated test assertions to use PackageNotFoundError instead of deprecated exception types

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[MGAMZ]

@HAOCHENYE This one is ready to be reviewed.

[HAOCHENYE]

Remove the lint modification

[MGAMZ]

OK, a follow-up commit is pushed.

[HAOCHENYE]

Besides，fix the lint.

You can follow https://github.com/open-mmlab/mmengine/blob/main/CONTRIBUTING.md to run lint locally

[MGAMZ]

I was misunderstanding your previous suggestion and disabled pre-commit 😆, restarting it soon.

[MGAMZ]

Lint is happy now.

yapf=0.32.0 requires lib2to3 which is deprecated since python=3.11, and is removed in python=3.13. 2to3 Doc

This issue cause contributors being unable to run yapf lint in python>=3.13. So I suggest upgrade the yapf version in pre-commit which no longer requires this deprecated lib.

[HAOCHENYE]

Lint is happy now.

yapf=0.32.0 requires lib2to3 which is deprecated since python=3.11, and is removed in python=3.13. 2to3 Doc

This issue cause contributors being unable to run yapf lint in python>=3.13. So I suggest upgrade the yapf version in pre-commit which no longer requires this deprecated lib.

Great job! Honestly, mmengine's lint configuration is outdated. I am considering replacing yapf with black or ruff after merging #1665.