optimize<AutoFetch>: reduce CPU usage

src/Commands/Fetch.cs

@@ -81,6 +81,8 @@ namespace SourceGit.Commands {
                         job.Cmd.Exec();
                         job.NextRunTimepoint = DateTime.Now.AddSeconds(_fetchInterval);
                     }
+
+                    Thread.Sleep(2000);
                 }
             });
         }

src/Views/Histories.axaml.cs

@@ -205,7 +205,7 @@ namespace SourceGit.Views {
 
     public partial class Histories : UserControl {
         public Histories() {
-            InitializeComponent();    
+            InitializeComponent();
         }
 
         protected override void OnUnloaded(RoutedEventArgs e) {