"update codeowners" workflow failing

[gsnedders]

See e.g., https://github.com/web-platform-tests/wpt/actions/runs/14896848751/job/41840938752

  cd wpt
  ./wpt update-codeowners ../wpt-metadata
  shell: /usr/bin/bash -e {0}
  env:
    pythonLocation: /opt/hostedtoolcache/Python/3.12.10/x64
    PKG_CONFIG_PATH: /opt/hostedtoolcache/Python/3.12.10/x64/lib/pkgconfig
    Python_ROOT_DIR: /opt/hostedtoolcache/Python/3.12.10/x64
    Python2_ROOT_DIR: /opt/hostedtoolcache/Python/3.12.10/x64
    Python3_ROOT_DIR: /opt/hostedtoolcache/Python/3.12.10/x64
    LD_LIBRARY_PATH: /opt/hostedtoolcache/Python/3.12.10/x64/lib
Traceback (most recent call last):
  File "/home/runner/work/wpt/wpt/wpt/./wpt", line 10, in <module>
    wpt.main()
  File "/home/runner/work/wpt/wpt/wpt/tools/wpt/wpt.py", line 210, in main
    venv = setup_virtualenv(main_args.venv, main_args.skip_venv_setup, props)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/work/wpt/wpt/wpt/tools/wpt/wpt.py", line 169, in setup_virtualenv
    venv.install_requirements(*props.get("requirements", []))
  File "/home/runner/work/wpt/wpt/wpt/tools/wpt/virtualenv.py", line 168, in install_requirements
    with open(requirements_path) as f:
         ^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '/home/runner/work/wpt/wpt/wpt/tools/ci/../wpt/requirements_metadata.txt'

This slipped through from #51318, which added these commands but didn't add a requirements file.