Allow accessing staging project show page without being logged in

There is no reason to require being logged in to obs, in order
to see the content of the staging project show page.

Fixes #7353

src/api/app/controllers/webui/staging/projects_controller.rb

@@ -1,7 +1,7 @@
 module Webui
   module Staging
     class ProjectsController < WebuiController
-      before_action :require_login
+      before_action :require_login, except: :show
       before_action :set_staging_workflow
       after_action :verify_authorized, except: :show