PF-1408 slsaprovenance was not good enough must use slsaprovenance1 as type

[kiversen]

When signing the image we also add the slsa provenance data like this:

cosign attest --yes --predicate ./provenance.json --type slsaprovenance "${{ steps.set-image-name.outputs.image-name }}@${DIGEST}"
But when we are verifying, with kyverno, we expects the slsa provenance data to be compliant with slsa provenance v1.

We must explicitly use the slsaprovenance1 when defining the type:

 --type='custom':     
specify a predicate type     

(slsaprovenance|slsaprovenance02|slsaprovenance1|link|spdx|spdxjson|cyclonedx|vuln|openvex|custom) or an URI

The correct cosign command should be:

cosign attest --yes --predicate ./provenance.json --type slsaprovenance1 "${{ steps.set-image-name.outputs.image-name }}@${DIGEST}"