Removed unnecessary property

Author: Sergio0694

Microsoft.Toolkit.Mvvm/Messaging/WeakRefMessenger.cs

@@ -420,15 +420,6 @@ public ReadOnlySpan<T> Span
                 get => this.array.AsSpan(0, this.index);
             }
 
-            /// <summary>
-            /// Gets the current number of items.
-            /// </summary>
-            public int Count
-            {
-                [MethodImpl(MethodImplOptions.AggressiveInlining)]
-                get => this.index;
-            }
-
             /// <summary>
             /// Adds a new item to the current collection.
             /// </summary>