fix(helm): update chart cilium to 1.15.6 (#1517)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

bootstrap/templates/kubernetes/apps/kube-system/cilium/app/helmrelease.yaml.j2

@@ -8,7 +8,7 @@ spec:
   chart:
     spec:
       chart: cilium
-      version: 1.15.5
+      version: 1.15.6
       sourceRef:
         kind: HelmRepository
         name: cilium

bootstrap/templates/kubernetes/bootstrap/helmfile.yaml.j2

@@ -22,7 +22,7 @@ releases:
   - name: cilium
     namespace: kube-system
     chart: cilium/cilium
-    version: 1.15.5
+    version: 1.15.6
     values:
       - ../apps/kube-system/cilium/app/helm-values.yaml
     needs: