Python 3.8 installs fine but has build issues

I got ahead of myself too quickly in: https://github.com/pydot/pydot/commit/8fc4016640fc4d0fa50f701d57694428184c1d3c

I tested it locally with tox and it worked on 3.8.
But I forgot about the important fact that the CI not only runs the 3.8 tests on tox, but that the *tox itself* is on 3.8. I'm not sure, but this might be the difference that makes the current CI fail.

In short, I fixed the deprecation warnings, but that broke the manual build for 3.8.
3.8 users can install pydot with no problems, but they probably can't build it from source.

Since 3.8 is deprecated, EOL, and [used to download pydot very rarely](https://pypistats.org/packages/pydot), I wonder if we should care. There's a good chance no one will ever use 3.8 to *build* pydot.
So I'm wondering how to fix this in our CI. Or maybe go back to the deprecated methods (we have time until Feb 2026 to change that).

Anyway, that was stupid to do right before a release!

@ferdnyc 

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