fix: Prepares for IPooledEnumerable removal (#1548)

### Summary

- Removes `IPooledEnumerable` (non-generic)
- Changes `IPooledEnumerable<T>` so that  `Free()` is replaced with the `IDisposable` pattern

Projects/UOContent/Items/Skill Items/Misc/FireHorn.cs

@@ -115,8 +115,6 @@ public partial class FireHorn : Item
             }
         }
 
-        eable.Free();
-
         if (targets.Count > 0)
         {
             var prov = from.Skills.Provocation.Fixed;