Remove redundant #nullable enable (#4275)

Content.Server/Voting/Managers/IVoteManager.cs

@@ -2,7 +2,6 @@
 using System.Diagnostics.CodeAnalysis;
 using Robust.Server.Player;
 
-#nullable enable
 
 namespace Content.Server.Voting.Managers
 {

Content.Server/Voting/Managers/VoteManager.DefaultVotes.cs

@@ -1,5 +1,4 @@
-#nullable enable
-using System;
+using System;
 using System.Collections.Generic;
 using Content.Server.GameTicking;
 using Content.Shared;

Content.Server/Voting/Managers/VoteManager.cs

@@ -20,7 +20,6 @@ using Robust.Shared.Network;
 using Robust.Shared.Timing;
 using Robust.Shared.Utility;
 
-#nullable enable
 
 namespace Content.Server.Voting.Managers
 {