Handle empty example test collection in CI

[sylvesterkaczmarek]

Summary

Keep the test-examples workflow green when examples/ currently contains no pytest tests, while still running example tests when they exist.

The original failure reported in #316 involved the now-removed Gym/RLlib examples. Those directories were removed from main, but the workflow still runs pytest examples. On current main, pytest collects zero tests and exits with status 5, causing test-examples to fail for otherwise unrelated pull requests.

This change:

• continues to run pytest examples
• treats only pytest exit status 5 (NO_TESTS_COLLECTED) as success
• propagates real collection and test failures
• leaves the existing example lint and typecheck steps unchanged

Fixes #316.

Validation

Rebased onto current main as a single focused commit (6486ad478df064f16fa3443a3f7babfb889c1d28).

GitHub Actions on the rebased head:

• test-examples: passed
• CodeQL: passed
• Google GitHub Admin Actions Workflow Security Scan: passed

The final diff changes only .github/workflows/test-examples.yml with 10 additions and 1 deletion.

[jzleibo]

This looks good to me, but something seems to be blocking the merge, I'm not sure what the issue is. I'll ask around..

[sylvesterkaczmarek]

Hi @jzleibo, just a quick follow-up on this. You mentioned you'd ask around about what was blocking the merge. The visible checks on the current head are all green and the PR is still mergeable from GitHub's side.

Have you heard anything about the remaining blocker?

Thanks again for taking a look.