Fix wrong partner_id refs in Project demo data

addons/project/project_demo.xml

@@ -50,8 +50,8 @@
             <field name="user_id" ref="base.user_demo"/>
             <field name="alias_model">project.task</field>
             <field name="message_follower_ids" eval="[(6, 0, [
-                    ref('base.user_root'),
-                    ref('base.user_demo')])]"/>
+                    ref('base.partner_root'),
+                    ref('base.partner_demo')])]"/>
         </record>
 
         <!-- We assign after so that default values applies -->