Fix json web requests having incorrect user agents

osu.Game/Online/API/OsuJsonWebRequest.cs

@@ -0,0 +1,21 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.IO.Network;
+
+namespace osu.Game.Online.API
+{
+    public class OsuJsonWebRequest<T> : JsonWebRequest<T>
+    {
+        public OsuJsonWebRequest(string uri)
+            : base(uri)
+        {
+        }
+
+        public OsuJsonWebRequest()
+        {
+        }
+
+        protected override string UserAgent => "osu!";
+    }
+}