Remove obsolete SLSA workflow

[lachlanharrisdev]

Description

Remove the slsa_generator.yml workflow, which has been made obsolete in favour of immutable releases built into GitHub

Checklist

Please ensure the following before requesting a merge:

• I have read and agree to the repository's CONTRIBUTING.md and LICENSE.md.
• All tests pass locally (make, make test).
• Relevant documentation has been updated (README.md, GitHub wiki(s)).
• Code follows the repository's style and formatting guidelines.
• I have added/updated relevant tests.

Related Issues

None provided.

Additional Notes

None provided.

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• Your contribution will be credited in the repository's contributor list and may be included in a major release.
• Individual contributions may not be credited in associated research publications.
• You confirm that you have the right to submit this work and that it does not violate any third-party rights or agreements.
• All contributions are made under the terms of the repository's license.
• If you violate any of the terms above or as outlined in CONTRIBUTING.md, your future contributions may not be accepted

[Copilot]

Pull Request Overview

This PR removes the obsolete SLSA generator workflow file in favor of GitHub's built-in immutable releases feature.

• Removes the entire .github/workflows/slsa-generator.yml workflow file
• Eliminates the custom SLSA provenance generation process that was previously used for supply chain security
• Simplifies the CI/CD pipeline by leveraging GitHub's native security features

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[lachlanharrisdev]

Just wanted to test how biased copilot is...