10.2.1: pytest fails in `jaraco/packaging/print-metadata.py::packaging.print-metadata.main` units

10.2.0 was OK.
```console
+ PYTHONPATH=/home/tkloczko/rpmbuild/BUILDROOT/python-jaraco-packaging-10.2.1-2.fc37.x86_64/usr/lib64/python3.10/site-packages:/home/tkloczko/rpmbuild/BUILDROOT/python-jaraco-packaging-10.2.1-2.fc37.x86_64/usr/lib/python3.10/site-packages
+ /usr/bin/pytest -ra -m 'not network'
============================= test session starts ==============================
platform linux -- Python 3.10.14, pytest-8.2.2, pluggy-1.5.0
rootdir: /home/tkloczko/rpmbuild/BUILD/jaraco.packaging-10.2.1
configfile: pytest.ini
plugins: mypy-0.10.3
collected 5 items

jaraco/packaging/metadata.py .. [ 40%]
jaraco/packaging/print-metadata.py F [ 60%]
jaraco/packaging/sphinx.py .. [100%]

=================================== FAILURES ===================================
___________________ [doctest] packaging.print-metadata.main ____________________
005
006 >>> main()
UNEXPECTED EXCEPTION: ModuleNotFoundError("No module named 'packaging.version'")
Traceback (most recent call last):
File "/usr/lib64/python3.10/doctest.py", line 1350, in __run
exec(compile(example.source, filename, "single",
File "", line 1, in
File "/home/tkloczko/rpmbuild/BUILD/jaraco.packaging-10.2.1/jaraco/packaging/print-metadata.py", line 9, in main
md = metadata.load('.')
File "/home/tkloczko/rpmbuild/BUILD/jaraco.packaging-10.2.1/jaraco/packaging/metadata.py", line 15, in load
return util.project_wheel_metadata(source_dir, isolated, **kwargs)
File "/usr/lib/python3.10/site-packages/build/util.py", line 42, in project_wheel_metadata
with DefaultIsolatedEnv() as env:
File "/usr/lib/python3.10/site-packages/build/env.py", line 90, in __enter__
self._env_backend = _PipBackend()
File "/usr/lib/python3.10/site-packages/build/env.py", line 153, in __init__
self._create_with_virtualenv = not self._has_valid_outer_pip and self._has_virtualenv
File "/usr/lib64/python3.10/functools.py", line 981, in __get__
val = self.func(instance)
File "/usr/lib/python3.10/site-packages/build/env.py", line 162, in _has_valid_outer_pip
return _has_dependency('pip', '22.3')
File "/usr/lib/python3.10/site-packages/build/env.py", line 46, in _has_dependency
from packaging.version import Version
ModuleNotFoundError: No module named 'packaging.version'
/home/tkloczko/rpmbuild/BUILD/jaraco.packaging-10.2.1/jaraco/packaging/print-metadata.py:6: UnexpectedException
=============================== warnings summary ===============================
jaraco/packaging/sphinx.py::packaging.sphinx._load_metadata_from_wheel
/home/tkloczko/rpmbuild/BUILD/jaraco.packaging-10.2.1/jaraco/packaging/sphinx.py:100: DeprecationWarning: JARACO_PACKAGING_SPHINX_WHEEL is deprecated; use BUILD_ENVIRONMENT=current instead
warnings.warn(

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
=========================== short test summary info ============================
FAILED jaraco/packaging/print-metadata.py::packaging.print-metadata.main
==================== 1 failed, 4 passed, 1 warning in 0.77s ====================
```

Run pytest -ra -m 'not network' and start with jaraco/packaging/print-metadata.py::packaging.print-metadata.main. Trace its call into jaraco/packaging/metadata.py and the reported build environment dependency failure. Done means the doctest passes without the ModuleNotFoundError and the remaining tests stay green.

Written by the indexing model from the issue text.