change threshold for failure

Author: jamesc-grafana

.github/workflows/self-zizmor.yaml

@@ -17,3 +17,4 @@ jobs:
     uses: grafana/shared-workflows/.github/workflows/reusable-zizmor.yml@8fa210559ab2cc62e7b12d3bb9cba19dbc862c11
     with:
       runs-on: ${{ !github.event.repository.private && 'ubuntu-latest' || 'ubuntu-arm64-small' }}
+      fail-severity: never