Change clipboard clear text to "<space>" instead of `string.Empty`. (#1172)

src/Android/Receivers/ClearClipboardAlarmReceiver.cs

@@ -8,7 +8,7 @@ namespace Bit.Droid.Receivers
         public override void OnReceive(Context context, Intent intent)
         {
             var clipboardManager = context.GetSystemService(Context.ClipboardService) as ClipboardManager;
-            clipboardManager.PrimaryClip = ClipData.NewPlainText("bitwarden", string.Empty);
+            clipboardManager.PrimaryClip = ClipData.NewPlainText("bitwarden", " ");
         }
     }
 }