Use package icon for packages feature in project sidebar

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/views/layouts/nav/sidebar/_project.html.haml

@@ -266,7 +266,7 @@
         = nav_link(controller: %w[projects/packages/packages]) do
           = link_to project_packages_path(@project) do
             .nav-icon-container
-              = sprite_icon('disk')
+              = sprite_icon('package')
             %span.nav-item-name
               = _('Packages')
           %ul.sidebar-sub-level-items.is-fly-out-only