gh-137754: Fix import of zoneinfo if _datetime is not available

[serhiy-storchaka]

Both modules should use the Python implementation in that case.

• Issue: _pydatetime rejects ZoneInfo as tzinfo yet C datetime accepts #137754

[AA-Turner]

Windows is failing as it can't find Europe/Paris, maybe the test should be skipped:

Traceback (most recent call last):
  File "D:\a\cpython\cpython\Lib\zoneinfo\_common.py", line 12, in load_tzdata
    path = resources.files(package_name).joinpath(resource_name)
           ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
  File "D:\a\cpython\cpython\Lib\importlib\resources\_common.py", line 46, in wrapper
    return func(anchor)
  File "D:\a\cpython\cpython\Lib\importlib\resources\_common.py", line 56, in files
    return from_package(resolve(anchor))
                        ~~~~~~~^^^^^^^^
  File "D:\a\cpython\cpython\Lib\functools.py", line 982, in wrapper
    return dispatch(args[0].__class__)(*args, **kw)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
  File "D:\a\cpython\cpython\Lib\importlib\resources\_common.py", line 82, in _
    return importlib.import_module(cand)
           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "D:\a\cpython\cpython\Lib\importlib\__init__.py", line 88, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1398, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1371, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1314, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 491, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1398, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1371, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1314, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 491, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1398, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1371, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1335, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'tzdata'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<string>", line 6, in <module>
    tzinfo = zoneinfo.ZoneInfo('Europe/Paris')
  File "D:\a\cpython\cpython\Lib\zoneinfo\_zoneinfo.py", line 43, in __new__
    instance = cls._weak_cache.setdefault(key, cls._new_instance(key))
                                               ~~~~~~~~~~~~~~~~~^^^^^
  File "D:\a\cpython\cpython\Lib\zoneinfo\_zoneinfo.py", line 70, in _new_instance
    file_obj = _common.load_tzdata(key)
  File "D:\a\cpython\cpython\Lib\zoneinfo\_common.py", line 29, in load_tzdata
    raise ZoneInfoNotFoundError(f"No time zone found with key {key}")
zoneinfo._common.ZoneInfoNotFoundError: 'No time zone found with key Europe/Paris'

[miss-islington-app]

Thanks @serhiy-storchaka for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

[bedevere-app]

GH-138084 is a backport of this pull request to the 3.14 branch.

[bedevere-app]

GH-138085 is a backport of this pull request to the 3.13 branch.