Fix move item bug introduced in the previous commit

Author: olsh

src/Todoist.Net.Tests/Services/ItemsServiceTests.cs

@@ -136,7 +136,7 @@ public void MoveItemsToProject_Success()
             client.Items.UpdateAsync(item).Wait();
 
             var project = new Project(Guid.NewGuid().ToString());
-            client.Projects.AddAsync(project);
+            client.Projects.AddAsync(project).Wait();
 
             var itemInfo = client.Items.GetAsync(item.Id).Result;
 
@@ -193,7 +193,7 @@ public void CreateNewItem_DueDateIsLocal_DueDateNotChanged()
 
             var itemInfo = client.Items.GetAsync(taskId).Result;
 
-            Assert.Equal(item.DueDate.Date, itemInfo.Item.DueDate.Date.Value.ToLocalTime());
+            Assert.Equal(item.DueDate.Date, itemInfo.Item.DueDate.Date?.ToLocalTime());
 
             client.Items.DeleteAsync(item.Id).Wait();
         }

src/Todoist.Net/Models/ItemMoveArgument.cs

@@ -6,7 +6,7 @@ namespace Todoist.Net.Models
     /// Represents a item move argument.
     /// </summary>
     /// <seealso cref="Todoist.Net.Models.MoveArgument" />
-    public class ItemMoveArgument : MoveArgument
+    public class ItemMoveArgument : BaseEntity
     {
         internal ItemMoveArgument()
         {
@@ -30,6 +30,11 @@ internal ItemMoveArgument()
         [JsonProperty("section_id")]
         public ComplexId? SectionId { get; internal set; }
 
+        /// <summary>Gets the parent entity identifier.</summary>
+        /// <value>The parent entity identifier.</value>
+        [JsonProperty("parent_id")]
+        public ComplexId? ParentId { get; internal set; }
+
         /// <summary>
         /// Creates the move to project argument.
         /// </summary>