Create a GitHub Actions workflow for verifying bundled libexpat files

[illia-v]

Feature or enhancement

A GitHub Actions workflow can be used to verify libexpat files bundled in CPython in Modules/expat/.

Pitch

When a new version of libexpat is released, someone usually creates a pull request to update its files bundled in CPython. Before merging it, a few people verify the change manually like in #98742.

An automatic test can be used for verifying the files during updates to reduce error proneness and speed up integration of new libexpat releases that fix security issues often.

We have a similar workflow for verifying bundled pip and setuptools wheels #91172.

Linked PRs

• gh-100538: Create a workflow for verifying bundled libexpat files #100539