Fix and enhance SBOM and SLSA (#282)
### SBOM and SLSA Generation Improvements
- Extended capabilities of existing SBOM functionality
- In some cases, SLSA was failing to complete, this is now fixed.
**Image Attestation**
- New image attestation functionality for enhanced security verification
- Ensures image integrity through cryptographic validation
- Public keys are now located in the /certs directory for verification purposes
- Centralizes access to verification materials
**New Verification Script**
- Added new certs/verify-image.sh script to help users verify SBOM and SLSA attestations
- Simplifies the verification process
### Component Updates
- Updated Dagger APKO components to newer version
