Always log missing official build attribute

osu.Game/OsuGame.cs

@@ -8,6 +8,7 @@ using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
+using System.Reflection;
 using System.Threading;
 using System.Threading.Tasks;
 using Humanizer;
@@ -871,6 +872,9 @@ namespace osu.Game
         {
             base.LoadComplete();
 
+            if (RuntimeInfo.EntryAssembly.GetCustomAttribute<OfficialBuildAttribute>() == null)
+                Logger.Log(NotificationsStrings.NotOfficialBuild.ToString());
+
             var languages = Enum.GetValues<Language>();
 
             var mappings = languages.Select(language =>