chore(container): update ghcr.io/prometheus-community/charts/kube-prometheus-stack docker tag to v81.6.3

Signed-off-by: budimanjojo-bot <111944664+budimanjojo-bot[bot]@users.noreply.github.com>

Author: budimanjojo-bot[bot]

cluster/apps/observability/kube-prometheus-stack/base/ocirepository.yaml

@@ -8,7 +8,7 @@ spec:
   interval: 15m
   url: oci://ghcr.io/prometheus-community/charts/kube-prometheus-stack
   ref:
-    tag: 81.2.2
+    tag: 81.6.3
   layerSelector:
     mediaType: application/vnd.cncf.helm.chart.content.v1.tar+gzip
     operation: copy