Remove redundant #nullable enable (#4275)

Content.Shared/Alert/AlertManager.cs

@@ -1,5 +1,4 @@
-#nullable enable
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;

Content.Shared/Alert/AlertOrderPrototype.cs

@@ -1,5 +1,4 @@
-#nullable enable
-using System;
+using System;
 using System.Collections.Generic;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Serialization;

Content.Shared/Alert/AlertPrototype.cs

@@ -1,5 +1,4 @@
-#nullable enable
-using System;
+using System;
 using System.Globalization;
 using Robust.Shared.Log;
 using Robust.Shared.Prototypes;

Content.Shared/Alert/AlertType.cs

@@ -1,5 +1,4 @@
-#nullable enable
-namespace Content.Shared.Alert
+namespace Content.Shared.Alert
 {
     /// <summary>
     /// Every category of alert. Corresponds to category field in alert prototypes defined in YML

Content.Shared/Alert/IAlertClick.cs

@@ -1,5 +1,4 @@
-#nullable enable
-using System;
+using System;
 using Robust.Shared.GameObjects;
 
 namespace Content.Shared.Alert

Content.Shared/Alert/SharedAlertsComponent.cs

@@ -1,4 +1,3 @@
-#nullable enable
 using System;
 using System.Collections.Generic;
 using Robust.Shared.GameObjects;