lxml==5.2.1 wheel is broken on macOS with CPython 3.8

[William Woodruff]

I'm filing this based on a locally observed breakage, reproduced from a breakage in pypa/twine's CI: <https://github.com/pypa/twine/pull/1096>. This was originally observed as a mysterious failure within `mypy` to find the `lxml` package, despite `lxml` being installed into the active virtual environment.

TL;DR: importing `etree` from `lxml` causes an `ImportError` on a missing symbol: `_exsltDateXpathCtxtRegister`

Here's the full traceback, from `pip install lxml==5.2.1` on CPython 3.8.18 on macOS:

```
>>> from lxml import etree
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: dlopen(/Users/william/tmp/env/lib/python3.8/site-packages/lxml/etree.cpython-38-darwin.so, 0x0002): symbol not found in flat namespace '_exsltDateXpathCtxtRegister'
```

Reproduction steps (using `pyenv` to bootstrap Python 3.8):

```
pyenv install 3.8.18
pyenv shell 3.8.18
python -m venv env && source env/bin/activate
python -m pip install lxml==5.2.1
python -c 'from lxml import etree'
```

This failure does **not** happen with `lxml==5.2.0`, strongly suggesting a wheel build regression on macOS (and possibly other platforms) between 5.2.0 and 5.2.1.

As a result of this bug, I'm unable to submit the library version metadata suggested in the issue template. However, the wheel in question is `lxml-5.2.1-cp38-cp38-macosx_10_9_universal2.whl`, which is on PyPI here: <https://files.pythonhosted.org/packages/ed/2e/c2efd8da53ea4c17d20bc12db17509ec5f46a7093599c067bac22d414e0b/lxml-5.2.1-cp38-cp38-macosx_10_9_universal2.whl>.

[William Woodruff (cptyossarian)]

From looking through recent changes, it appears that the 3.8 wheel is known to be broken and was intentionally skipped in `cibuildwheel`: <https://github.com/lxml/lxml/commit/dd85a2dc13221a509da198d5297ee4667ec4aa7e>

However, that change was made prior to 5.2.1's release, meaning that the current wheel on PyPI is still non-functional. I believe yanking that individual wheel would suffice to resolve this issue, given that future releases will not build this wheel at all.