Async task OnUpdate (#355)

* Make OnUpdate a task instead a void, handle OnUpdate better by running it in it's own task

* Make helper transient, resolve mod loading issues

Libraries/SPTarkov.Server.Core/Callbacks/SaveCallbacks.cs

@@ -22,14 +22,13 @@ public class SaveCallbacks(
         _saveServer.Load();
     }
 
-    public bool OnUpdate(long timeSinceLastRun)
+    public Task OnUpdate(long timeSinceLastRun)
     {
         if (timeSinceLastRun > _coreConfig.ProfileSaveIntervalInSeconds)
         {
             _saveServer.Save();
-            return true;
         }
 
-        return false;
+        return Task.CompletedTask;
     }
 }