[IMP] project: improve Warning message for task recursion

Use same as other _check_recursion error messages

closes odoo/odoo#33125

Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>

addons/project/i18n/project.pot

@@ -584,7 +584,7 @@ msgstr ""
 
 #. module: project
 #: constraint:project.task:0
-msgid "Circular references are not permitted between tasks and sub-tasks"
+msgid "You cannot create recursive tasks."
 msgstr ""
 
 #. module: project

addons/project/models/project.py

@@ -530,7 +530,7 @@ class Task(models.Model):
     @api.constrains('parent_id')
     def _check_parent_id(self):
         if not self._check_recursion():
-            raise ValidationError(_('Circular references are not permitted between tasks and sub-tasks'))
+            raise ValidationError(_('You cannot create recursive tasks.'))
 
     def _compute_attachment_ids(self):
         for task in self: