Generate a SBOM and SLSA attestations during the release workflow

[akafredperry]

Is your feature request related to a problem? Please describe.

We should be generating an SBOM and SLSA attestations during the release workflow

Describe the solution you'd like

PR review feedback from #378
We should be generating an SBOM and SLSA attestations during the release workflow (though I'm happy to do that as a standalone piece of work once the basic mechanics are in place).

https://github.com/atsign-foundation/noports/blob/trunk/.github/workflows/npt_flutter_release.yaml is a good example of a workflow where we've recently added that stuff.

Describe alternatives you've considered

No response

Additional context

No response

[cpswan]

SBOM Component ID for this in sbomify is hXAJhdj5V9ZT

[cpswan]

Moving to PR136 for when @akafredperry is back