feat(container): update thanos ( 12.20.3 → 12.21.0 ) (#4007)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [thanos](https://togithub.com/bitnami/charts)
([source](https://togithub.com/bitnami/charts/tree/HEAD/bitnami/thanos))
| minor | `12.20.3` -> `12.21.0` |

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kubernetes/kyak/apps/monitoring/thanos/app/helmrelease.yaml

@@ -10,7 +10,7 @@ spec:
   chart:
     spec:
       chart: thanos
-      version: 12.20.3
+      version: 12.21.0
       sourceRef:
         kind: HelmRepository
         name: bitnami