title: Odoo - Filter users with specific group in many2one
body: <p>I am trying to create a drop-down in my custom module form where i want to show users from a specific group</p>
  
  <pre><code>fields.Many2one('res.user',string="Admins", domain=[('groups_id','=',12)])
  </code></pre>
  
  <p>this is what i tried, adding a domain but it is not working.</p>
  
  <p>I want to show all user who are admins in this drop-down.</p>