build: adding provenance generation to release-please workflow

[rsoberano-ld]

Requirements

• [ ] 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

Related issues

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Describe the solution you've provided

Using Github SLSA generator to generate build provenance for python-server-sdk

Implementation based off of previous SDK SLSA integrations with release-please and Python-specific guidance here: https://sethmlarson.dev/python-and-slsa#generating-a-provenance-attestation

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Additional context

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[rsoberano-ld]

@keelerm84 does the manual-publish.yml workflow publish anything to Github releases?

[keelerm84]

@keelerm84 does the manual-publish.yml workflow publish anything to Github releases?

It probably uploads a compressed copy of the source code, but the actual publication of the package is handled through pypi.