Allow the vulnix pipeline to fail but propagate the code

ci-tools/vulnerability-scan

@@ -35,4 +35,5 @@ fi
 # GitLab to allow this by setting `allow_failure` to true in the GitLab CI
 # config.
 set +eo pipefail
-nix-shell -p vulnix --run 'vulnix ./scan-target/' | tee "$OUTPUT"
+status=$(nix-shell -p vulnix --run 'vulnix ./scan-target/' | tee "$OUTPUT")
+exit $status