Update gsoci.azurecr.io/giantswarm/curl Docker tag to v8.18.0 (#405)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

helm/grafana/values.yaml

@@ -222,7 +222,7 @@ grafana:
   downloadDashboardsImage:
     registry: gsoci.azurecr.io
     repository: giantswarm/curl
-    tag: 8.17.0
+    tag: 8.18.0
     sha: ""
     pullPolicy: IfNotPresent