Update gatekeeper to 3.6.0

update "chart" (https://github.com/open-policy-agent/gatekeeper) from "v3.5.2" (5733cf33442d2c9485f59c181117c09e588da6cb) to "v3.6.0" (9503ef2307225c5f6e8d97e312efb008a26e36bb)

https://repo1.dso.mil/platform-one/big-bang/bigbang/-/issues/747

chart/templates/_helpers.tpl

@@ -24,6 +24,16 @@ If release name contains chart name it will be used as a full name.
 {{- end -}}
 {{- end -}}
 
+
+{{/*
+Create imagePullSecret related to bug in 3.6.0
+*/}}
+{{- define "private-registry" }}
+{{- with .Values.imageCredentials }}
+{{- printf "{\"auths\":{\"%s\":{\"username\":\"%s\",\"password\":\"%s\",\"email\":\"%s\",\"auth\":\"%s\"}}}" .registry .username .password .email (printf "%s:%s" .username .password | b64enc) | b64enc }}
+{{- end }}
+{{- end }}
+
 {{/*
 Create chart name and version as used by the chart label.
 */}}