fix(helm): update chart nextcloud to 4.6.8 (#6079)

| datasource | package   | from  | to    |
| ---------- | --------- | ----- | ----- |
| helm       | nextcloud | 4.6.7 | 4.6.8 |

Co-authored-by: rosey-the-renovator-bot[bot] <98764075+rosey-the-renovator-bot[bot]@users.noreply.github.com>

kubernetes/main/apps/collab/nextcloud/app/helmrelease.yaml

@@ -11,7 +11,7 @@ spec:
     spec:
       # renovate: registryUrl=https://nextcloud.github.io/helm/
       chart: nextcloud
-      version: 4.6.7
+      version: 4.6.8
       sourceRef:
         kind: HelmRepository
         name: nextcloud-charts