Attestations for
  ghcr.io/boks-sh/ruby@sha256:88fca90fd169d01a0c0ed326b91446c1156e72f8bc47f797213d5b33d26c046a

Verify them yourself:
  cosign verify-attestation --key cosign.pub \
      --type <cyclonedx|slsaprovenance> ghcr.io/boks-sh/ruby@sha256:88fca90fd169d01a0c0ed326b91446c1156e72f8bc47f797213d5b33d26c046a

=== cyclonedx ===================================================
  (no attestation matches the document published now -- 0 older one(s) are attached)

=== slsaprovenance ==============================================
  (no attestation matches the document published now -- 0 older one(s) are attached)