Fix rootio quality gate: replace cassandra with python test image, add labels

  - Replace cassandra test image with docker.io/rootpublic/python:3.11-slim-bookworm
  - Update expected namespaces to include debian:12 and github:language:python
  - Update vulnerability-match-labels submodule with new ubuntu TP/FP labels
  - Remove cassandra label files

Signed-off-by: Chai Tadmor <chai.tadmor@root.io>

Author: chait-slim

labels/docker.io+rootpublic+cassandra:latest@sha256:02272b14efbe14e70ee5512ce707c4e300d3c1813f0e5df9562512c1b96be835/0e40029f-9d89-4014-a1ab-6a91f764467d.json

@@ -0,0 +1 @@
+{"ID": "00abceac-4644-41cd-b060-f152055d2b6a", "effective_cve": "CVE-2016-2781", "image": {"exact": "docker.io/rootpublic/ubuntu@sha256:1390a26823a5a761dfbb7f591ae74a71afd8e23583a2f0c58dca6943b606f6d5"}, "label": "FP", "note": "Ubuntu marks this negligible/won't-fix; grype[custom-db] correctly suppresses it via unaffectedPackageHandles", "package": {"name": "coreutils", "version": "8.32-4.1ubuntu1.2"}, "timestamp": "2026-04-06T00:00:00.000000+00:00", "user": "chaislim", "vulnerability_id": "CVE-2016-2781"}

labels/docker.io+rootpublic+cassandra:latest@sha256:02272b14efbe14e70ee5512ce707c4e300d3c1813f0e5df9562512c1b96be835/325103c9-63a1-43d5-b562-35ec69e69d46.json

@@ -0,0 +1 @@
+{"ID": "36d92542-fe48-4bc7-b43f-40822798d161", "effective_cve": "CVE-2017-11164", "image": {"exact": "docker.io/rootpublic/ubuntu@sha256:1390a26823a5a761dfbb7f591ae74a71afd8e23583a2f0c58dca6943b606f6d5"}, "label": "TP", "note": "Real vulnerability in libpcre3 that Root IO has not patched; grype[custom-db] correctly reports it", "package": {"name": "libpcre3", "version": "2:8.39-13ubuntu0.22.04.1"}, "timestamp": "2026-04-06T00:00:00.000000+00:00", "user": "chaislim", "vulnerability_id": "CVE-2017-11164"}