ninja: try add_header for ingress

basic/apps/ninja/invoiceninja-values-configmap.yaml

@@ -15,7 +15,7 @@ data:
       certManager: true
         annotations:
           nginx.ingress.kubernetes.io/configuration-snippet: |
-            more_set_headers "Content-Security-Policy: frame-ancestors 'self' ${nextcloud_domain}";
+            add_header "Content-Security-Policy: frame-ancestors 'self' ${nextcloud_domain}";
     persistence:
       public:
         existingClaim: invoiceninja-data