Pending upstream fix: vexctl: GHSA-4qg8-fj49-pxjh and GHSA-f83f-xpx7-ffpw

[debasishbsws]

GHSA-f83f-xpx7-ffpw:

          note: |
            The dependency github.com/sigstore/timestamp-authority cannot be updated from v1.2.9 to v2.0.3 because it is an indirect dependency
            pulled in by github.com/sigstore/cosign/v2, and the current cosign v2.x releases (up to v2.6.1) all depend on timestamp-authority v1.x;
            upgrading to cosign v3 to potentially get timestamp-authority v2 is not feasible as it introduces breaking API changes
            (e.g., sign.SignerFromKeyOpts is undefined), which would require significant refactoring of attestation.go and other signing-related code in vexctl.

GHSA-4qg8-fj49-pxjh:

          note: |
            The dependency github.com/sigstore/fulcio cannot be updated to v1.8.3 because the API has changed and
            cryptoutils.ValidatePubKey is now undefined; resolving this requires upgrading to cosign v3, which is
            not feasible as it introduces breaking API changes(e.g., sign.SignerFromKeyOpts is undefined) that
            would require significant refactoring of attestation.go and other signing-related code in vexctl.