chore: prevent sig from taking the latest tag

.github/workflows/docker-publish.yml

@@ -99,4 +99,5 @@ jobs:
           DIGEST: ${{ steps.build-and-push.outputs.digest }}
         # This step uses the identity token to provision an ephemeral certificate
         # against the sigstore community Fulcio instance.
-        run: echo "${TAGS}" | xargs -I {} cosign sign --yes {}@${DIGEST}
+        run: |
+          echo "${TAGS}" | grep -v "latest" | xargs -I {} cosign sign --yes {}@${DIGEST}