chore(deps): update helm release open-webui to v8

Author: renovate[bot]

kubernetes/apps/ai/open-webui/app/kustomization.yaml

@@ -7,7 +7,7 @@ resources:
 helmCharts:
   - name: open-webui
     repo: https://helm.openwebui.com/
-    version: 5.19.0
+    version: 8.12.2
     releaseName: open-webui
     namespace: ai
     valuesFile: values.yaml