Don't render link when user login is nil

When user login is nil, Rails renders the URL as link text instead.
To avoid this, the link is only rendered when user.login is present.

Author: blish-guenzler

app/views/alchemy/admin/users/_resource_table.html.erb

@@ -3,7 +3,7 @@
     <%= render_icon(:user, style: user.logged_in? ? "solid" : "regular") %>
   <% end %>
   <% table.column :login, sortable: true do |user| %>
-    <% if can?(:edit, user) %>
+    <% if can?(:edit, user) && user.login %>
       <%= link_to_dialog user.login,
         alchemy.edit_admin_user_path(user), {
           title: Alchemy.t(:edit_user),