Fix path for reusable-zizmor workflow

Updated the workflow to use the correct repository path for reusable-zizmor.yml.

Author: isaiah-grafana

.github/workflows/self-zizmor.yaml

@@ -47,7 +47,7 @@ jobs:
 
     # Pilot (#326): reusable from fork branch (not SHA) so ruleset testing tracks latest shared-workflows changes.
     # Swap back to grafana/shared-workflows@<SHA> on main when done.
-    uses: isaiah-grafana/shared-workflows/.github/workflows/reusable-zizmor.yml@feat/zizmor-vendor-excludes-326
+    uses: grafana/shared-workflows/.github/workflows/reusable-zizmor.yml@feat/zizmor-vendor-excludes-326
     with:
       runs-on: ${{ !github.event.repository.private && 'ubuntu-latest' || 'ubuntu-arm64-small' }}
       fail-severity: high