Add GitHub Issue Tests as a post-DuckDB report

[gaurav]

It would be a great way check how the new Babel build would affect the issues we face.

The way to implement this is:

• Make babel_validation a top-level import; add ruff and offline unit tests to CI TranslatorSRI/babel-validation#106
• Run BabelTest assertions embedded in GitHub issues as pytest tests TranslatorSRI/babel-validation#103
• Add babel-validation (via GitHub URL, we don't need to publish to pypi yet) as a dependency
• Add a report that runs at the end of all the DuckDB outputs, and then runs DuckDB queries to test all the GitHub issues