chore(attestation): update signed rules ledger

[github-actions]

Auto-generated by attest-rules.yml.

Updates attestations.json with the rule files that are new or
changed since the last attestation, and re-signs it keyless via
cosign/Sigstore using this workflow's ambient GitHub Actions OIDC
identity (logged to the public Rekor transparency log).

Verify independently before merging:

cosign verify-blob \
  --certificate attestations.json.pem \
  --signature attestations.json.sig \
  --certificate-identity "https://github.com/trustabl/trustabl-rules/.github/workflows/attest-rules.yml@refs/heads/main" \
  --certificate-oidc-issuer "https://token.actions.githubusercontent.com" \
  attestations.json