Merge pull request #479 from hcloud-k8s/renovate/cert-manager-1.x

chore(deps): update helm release cert-manager to v1.21.1

Author: M4t7e

variables.tf

@@ -2069,7 +2069,7 @@ variable "cert_manager_helm_chart" {
 
 variable "cert_manager_helm_version" {
   type        = string
-  default     = "v1.20.3"
+  default     = "v1.21.1"
   description = "Version of the Cert Manager Helm chart to deploy."
 }