python3Packages.mmengine: use setuptools._distutils instead of deprecated distutils

[GaetanLepage]

Things done

This fixes the following error identified when running nixpkgs-review on #419179.

>       from distutils import errors
E       ModuleNotFoundError: No module named 'distutils'

mmengine/utils/dl_utils/collect_env.py:54: ModuleNotFoundErro

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
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• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• Nixpkgs 25.11 Release Notes (or backporting 25.05 Nixpkgs Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
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• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other contributing documentation in corresponding paths.

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[GaetanLepage]

nixpkgs-review result

Generated using nixpkgs-review-gha

Command: nixpkgs-review pr 423183

Logs: https://github.com/GaetanLepage/nixpkgs-review-gha/actions/runs/16116184239

---

x86_64-linux

✅ 8 packages built:

• python312Packages.mmcv
• python312Packages.mmcv.dist
• python312Packages.mmengine
• python312Packages.mmengine.dist
• python313Packages.mmcv
• python313Packages.mmcv.dist
• python313Packages.mmengine
• python313Packages.mmengine.dist

---

aarch64-linux

✅ 8 packages built:

• python312Packages.mmcv
• python312Packages.mmcv.dist
• python312Packages.mmengine
• python312Packages.mmengine.dist
• python313Packages.mmcv
• python313Packages.mmcv.dist
• python313Packages.mmengine
• python313Packages.mmengine.dist

[SuperSandro2000]

That distutils is also kinda deprecated, I think like the whole of distutils.

https://setuptools.pypa.io/en/latest/deprecated/distutils/index.html

Not sure if the distutils package is deprecated (probably, too) but it is probably easier to just plot that in because setuptools might eventually drop that vendored distutils, too.

[GaetanLepage]

That distutils is also kinda deprecated, I think like the whole of distutils.

https://setuptools.pypa.io/en/latest/deprecated/distutils/index.html

Not sure if the distutils package is deprecated (probably, too) but it is probably easier to just plot that in because setuptools might eventually drop that vendored distutils, too.

Opened #424002.