feat(helm): update chart cert-manager to v1.20.2

Author: renovate[bot]

kubernetes/apps/cert-manager/cert-manager/app/helmrelease.yaml

@@ -10,7 +10,7 @@ spec:
   chart:
     spec:
       chart: cert-manager
-      version: v1.19.4
+      version: v1.20.2
       sourceRef:
         kind: HelmRepository
         name: jetstack