Add GitHub Action to prevent manual version bumps in PRs

[corbt]

This PR adds a GitHub Action workflow that prevents contributors from manually bumping the version in regular pull requests.

What it does:

• ✅ Runs on PRs that modify pyproject.toml
• ✅ Skips release PRs (branches starting with release/)
• ✅ Fails with clear instructions if version was manually changed
• ✅ Guides contributors to use the proper release workflow

Benefits:

• Enforces consistent release process
• Prevents accidental version conflicts
• Educates contributors on proper release workflow
• Reduces maintenance overhead

The workflow provides clear instructions to use:

gh workflow run create-draft-release.yml --field version_type=patch

Or the GitHub Actions web interface at: https://github.com/OpenPipe/ART/actions/workflows/create-draft-release.yml