update: upgrade Grafana chart to 8.X (#1794)

Co-authored-by: Raj Athavale <athavr@amazon.com>

Author: athavr

manifests/modules/observability/oss-metrics/.workshop/terraform/main.tf

@@ -145,7 +145,7 @@ module "grafana" {
 
   description      = "Grafana"
   chart            = "grafana"
-  chart_version    = "6.43.1"
+  chart_version    = var.grafana_chart_version
   namespace        = kubernetes_namespace.grafana.metadata[0].name
   create_namespace = false
   repository       = "https://grafana.github.io/helm-charts"

manifests/modules/observability/oss-metrics/.workshop/terraform/vars.tf

@@ -40,3 +40,10 @@ variable "operator_chart_version" {
   # renovate-helm: depName=opentelemetry-operator registryUrl=https://open-telemetry.github.io/opentelemetry-helm-charts
   default = "0.68.1"
 }
+
+variable "grafana_chart_version" {
+  description = "The chart version of grafana to use"
+  type        = string
+  # renovate-helm: depName=grafana registryUrl=https://grafana.github.io/helm-charts
+  default = "8.15.0"
+}