Don't consider version suffixes when checking for updates

This is just to make life easier for me with deploys for now.

osu.Game/Updater/SimpleUpdateManager.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Threading.Tasks;
 using Newtonsoft.Json;
 using osu.Framework;
@@ -41,11 +42,16 @@ protected override async Task<bool> PerformUpdateCheck()
 
                 var latest = releases.ResponseObject;
 
-                if (latest.TagName != version)
+                // avoid any discrepancies due to build suffixes for now.
+                // eventually we will want to support release streams and consider these.
+                version = version.Split('-').First();
+                var latestTagName = latest.TagName.Split('-').First();
+
+                if (latestTagName != version)
                 {
                     Notifications.Post(new SimpleNotification
                     {
-                        Text = $"A newer release of osu! has been found ({version} → {latest.TagName}).\n\n"
+                        Text = $"A newer release of osu! has been found ({version} → {latestTagName}).\n\n"
                                + "Click here to download the new version, which can be installed over the top of your existing installation",
                         Icon = FontAwesome.Solid.Upload,
                         Activated = () =>