Update gatekeeper to 3.9.0

Package Merge Request

Package Changes

https://repo1.dso.mil/platform-one/big-bang/apps/core/policy/-/blob/3.9.0-bb.0/CHANGELOG.md

Package MR

https://repo1.dso.mil/platform-one/big-bang/apps/core/policy/-/merge_requests/144

For Issue

Closes https://repo1.dso.mil/platform-one/big-bang/apps/core/policy/-/issues/166

Closes https://repo1.dso.mil/platform-one/big-bang/apps/core/policy/-/issues/168

chart/templates/gatekeeper/values.yaml

@@ -14,6 +14,11 @@ postInstall:
       pullPolicy: {{ .Values.imagePullPolicy }}
       pullSecrets:
       - name: private-registry
+  probeWebhook:
+    image:
+      pullPolicy: {{ .Values.imagePullPolicy }}
+      pullSecrets:
+      - name: private-registry
 postUpgrade:
   cleanupCRD:
     image: