fix: update status bar getting stuck empty after periodic update check (#4776)

Co-authored-by: Chris Nolan.ca <22640+ChrisNolan@users.noreply.github.com>

Author: ChrisNolan

Hearthstone Deck Tracker/Utility/Updating/Updater.Squirrel.cs

@@ -25,6 +25,11 @@ private static bool ShouldCheckForUpdates()
 
 		public static async void CheckForUpdates(bool force = false)
 		{
+			// An update has already been downloaded and installed, and is just waiting for a
+			// restart. Checking again would reset the status bar (UpdaterState.Checking/None
+			// both hide the "click to update" message) while leaving it visible but empty.
+			if(Status.UpdaterState == UpdaterState.Available)
+				return;
 			if(!force && !ShouldCheckForUpdates())
 				return;
 			_lastUpdateCheck = DateTime.Now;