Fixing warnings (#8131)

Content.Server/GameTicking/GameTicker.LobbyBackground.cs

@@ -1,19 +1,12 @@
-using System.IO;
-using System.Linq;
 using Content.Server.GameTicking.Prototypes;
-using Content.Shared.Audio;
-using Robust.Shared.ContentPack;
 using Robust.Shared.Random;
 using Robust.Shared.Utility;
-using Robust.Shared.ViewVariables;
-
+using System.Linq;
 
 namespace Content.Server.GameTicking;
 
 public sealed partial class GameTicker
 {
-    [Dependency] private readonly IResourceManager _resourceManager = default!;
-
     [ViewVariables]
     public string? LobbyBackground { get; private set; }
 
@@ -32,7 +25,6 @@ public sealed partial class GameTicker
         RandomizeLobbyBackground();
     }
 
-
     private void RandomizeLobbyBackground() {
         LobbyBackground = _lobbyBackgrounds!.Any() ? _robustRandom.Pick(_lobbyBackgrounds!).ToString() : null;
     }