Update grafana/grafana Docker tag to v12.0.2

Author: renovate[bot]

values.yaml

@@ -90,7 +90,7 @@ grafana:
     # -- Image repository for Grafana.
     repository: grafana/grafana
     # -- Tag for the Grafana image.
-    tag: 12.0.0-security-01
+    tag: 12.0.2-security-01
   credentials:
     # -- Name of an existing secret for Grafana credentials. Leave empty to create a new secret.
     existingSecretName: ""