adding task to root node (#11666)

diff --git a/erpnext/projects/doctype/task/task.py b/erpnext/projects/doctype/task/task.py
index fa56a95..52d9025 100644
--- a/erpnext/projects/doctype/task/task.py
+++ b/erpnext/projects/doctype/task/task.py
@@ -233,7 +233,7 @@
     })
     args = make_tree_args(**args)
 
-    if args.parent_task == 'task':
+    if args.parent_task == 'All Tasks':
         args.parent_task = None
 
     frappe.get_doc(args).insert()