Remove owned annotation from idx arg in insert

Co-authored-by: soraros <soraros@users.noreply.github.com>
Signed-off-by: bgreni <42788181+bgreni@users.noreply.github.com>

stdlib/src/collections/linked_list.mojo

@@ -422,7 +422,7 @@ struct LinkedList[
 
     fn insert[
         I: Indexer
-    ](mut self, owned idx: I, owned elem: ElementType) raises:
+    ](mut self, idx: I, owned elem: ElementType) raises:
         """
         Insert an element `elem` into the list at index `idx`.