[FIX] project: fix the visibility of assign to me button

Currently the 'Assign to me' button is never visible on form view
of the task.

So in this commit visible the button only when user_ids is Fasle on
task.

closes odoo/odoo#76967

Taskid: 2642872
Closes: #76312
X-original-commit: 6f96898160bb219427d5c5b23195ef8563e732a8
Related: odoo/enterprise#21072
Signed-off-by: LTU-Odoo <IT-Ideas@users.noreply.github.com>

addons/project/views/project_views.xml

@@ -785,7 +785,7 @@
                     <field name="allow_task_dependencies" invisible="1" />
                     <header>
                         <button name="action_assign_to_me" string="Assign to Me" type="object" class="oe_highlight"
-                            attrs="{'invisible' : [('user_ids', '!=', False)]}" data-hotkey="q"/>
+                            attrs="{'invisible' : [('user_ids', '!=', [])]}" data-hotkey="q"/>
                         <field name="stage_id" widget="statusbar" options="{'clickable': '1', 'fold_field': 'fold'}" attrs="{'invisible': [('project_id', '=', False), ('stage_id', '=', False)]}"/>
                     </header>
                     <div class="alert alert-info oe_edit_only mb-0" role="status" attrs="{'invisible': ['|', ('recurring_task', '=', False), ('recurrence_id', '=', False)]}">