Fix partial for update project notifications

app/views/projects/buttons/_notifications.html.haml

 - if @notification_setting
-  = form_for [@project.namespace.becomes(Namespace), @project, @notification_setting], remote: true, html: { class: 'inline', id: 'notification-form' } do |f|
+  = form_for @notification_setting, url: namespace_project_notification_setting_path(@project.namespace.becomes(Namespace), @project), remote: true, html: { class: 'inline', id: 'notification-form' } do |f|
     = f.hidden_field :level
     %span.dropdown
       %a.dropdown-new.btn.notifications-btn#notifications-button{href: '#', "data-toggle" => "dropdown"}