build: fixing provenance workflow by removing runs-on parameter which conflicts with uses

[rsoberano-ld]

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• [ ] I have added test coverage for new or changed functionality
• [ ] I have followed the repository's pull request submission guidelines
• [ ] I have validated my changes against all supported platform versions

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[rsoberano-ld]

Tested with manual publish dry run from branch: https://github.com/launchdarkly/ruby-server-sdk/actions/runs/7850356177