Bump test chart dependencies (#404)

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Co-authored-by: marcofranssen <[email protected]>

.github/tests/charts.json

@@ -2,12 +2,12 @@
   {
     "name": "kube-prometheus-stack",
     "repo": "https://prometheus-community.github.io/helm-charts",
-    "version": "61.5.0"
+    "version": "61.7.0"
   },
   {
     "name": "cert-manager",
     "repo": "https://charts.jetstack.io",
-    "version": "v1.15.1"
+    "version": "v1.15.2"
   },
   {
     "name": "ingress-nginx",