Fix race condition in TimerUpdateTrigger stop

RGB.NET.Core/Update/TimerUpdateTrigger.cs

@@ -92,13 +92,23 @@ namespace RGB.NET.Core
                 if (UpdateTask != null)
                 {
                     UpdateTokenSource?.Cancel();
+                    try
+                    {
                         // ReSharper disable once MethodSupportsCancellation
                         UpdateTask.Wait();
+                    }
+                    catch (AggregateException)
+                    {
+                        // ignored
+                    }
+                    finally
+                    {
                         UpdateTask.Dispose();
                         UpdateTask = null;
                     }
                 }
             }
+        }
 
         private void UpdateLoop()
         {