Use GitHub runners for x86 wheels

[andimarafioti]

Summary

• Move x86_64 CUDA wheel jobs back from hf-jobs-cpu-performance to ubuntu-24.04 in both the validation and publish workflows.
• Keep aarch64 wheel jobs on ubuntu-24.04-arm.
• Update the default qwentts.cpp checkout from 4536dcdce27c3764a93a06d6bf64026b124962f5 to latest master, 9dbe7ea26a01b30fccb117ae5e86807c1dc23d42.
• Update the README default commit reference to match the workflows.

Why

The HF Jobs path is not usable for this repo right now. GitHub reports zero self-hosted runners for andimarafioti/qwentts-cpp-python, and the v0.2.0 publish run left the x86_64 CUDA 12.8 job queued on hf-jobs-cpu-performance while the aarch64 GitHub-hosted job completed successfully.

I cancelled that stuck publish run so it does not keep blocking/noising the release state.

Validation

• git ls-remote https://github.com/ServeurpersoCom/qwentts.cpp HEAD refs/heads/master resolves latest master to 9dbe7ea26a01b30fccb117ae5e86807c1dc23d42.
• Parsed .github/workflows/wheels.yml and .github/workflows/publish.yml with PyYAML.
• Confirmed all x86_64 CUDA workflow entries now use ubuntu-24.04 with build_jobs: "2".
• uv run --with pytest pytest -q
• git diff --check

Release note

After this merges, the existing v0.2.0 tag points at the old workflow commit. Since 0.2.0 has not been published to PyPI, the clean release path is to move/recreate the v0.2.0 tag on the merged main commit and push it again, or create a new v0.2.1 release if you prefer never moving tags.