v0.13.1

SIGTERM on the gRPC server, plus dependency maintenance. No rule changes;
the catalog stays at 228 and any tag that validated on 0.13.0 validates identically
here.

Fixed

• vastlint-grpc now exits on SIGTERM as well as SIGINT, so Kubernetes can
  stop the process. The starter manifest also carries a liveness probe and
  resource bounds.

Changed

• sha2 0.10 to 0.11 (catalog digest).
• apache-avro 0.21 to 0.22. Event encoding uses GenericDatumWriter /
  GenericDatumReader.
• github/codeql-action/upload-sarif 4.37.6 to 4.37.7.

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