Fix rendering of staging workflow partial

The path to the delete partial changed in e415d23
because of the introduced Staging namespace.
Because the view code was not updated, this was breaking the
rendering of the staging workflow page.

src/api/app/views/webui2/webui/staging/workflows/show.html.haml

@@ -35,7 +35,7 @@
             %a{ data: { toggle: 'modal', target: '#delete-staging-workflow' }, href: '#' }
               %i.fas.fa-times-circle.text-danger
               Delete
-            = render(partial: 'webui2/webui/staging_workflows/delete', locals: { project: @project })
+            = render(partial: 'webui2/webui/staging/workflows/delete', locals: { project: @project })
   .col-xl-2
     = render partial: 'legend'
     = render partial: 'infos', locals: { staging_workflow: @staging_workflow, empty_projects: @empty_projects,