chore: use signed commits in ruby release workflow

[marandaneto]

💡 Motivation and Context

The Ruby release workflow currently pushes the version-bump commit with a normal git commit, but the repository requires verified signatures. That causes the release job to fail when it tries to push the release commit to main.

💚 How did you test it?

• Re-read the Python SDK release workflow and matched the same planetscale/ghcommit-action pattern in Ruby
• Parsed .github/workflows/release.yml with Ruby YAML to confirm the workflow file is still valid
• Verified the Ruby workflow now uses the returned commit-hash output to gate publish steps and create the tag from the exact signed commit

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran pnpm changeset to generate a changeset file
• Added the release label to the PR