Fix final unit test

Author: inputfalken

src/DynamoDBGenerator/Internal/MarshallHelper.cs

@@ -55,16 +55,14 @@ public static AttributeValue FromNullableNumberSet<T>(IEnumerable<T?> numbers, s
         if (numbers.TryGetNonEnumeratedCount(out var count) is false)
             return new AttributeValue
             {
-                NS = numbers
-                    .Select(x => x.ToString())
-                    .Where(x => string.IsNullOrEmpty(x) is false).ToList()
+                NS = numbers.Select(number => number?.ToString()).ToList()
             };
 
         if (count is 0)
             return new AttributeValue { NS = [] };
 
         var list = new List<string?>(count);
-        list.AddRange(numbers.Select(x => x.ToString()).Where(x => string.IsNullOrEmpty(x) is false));
+        list.AddRange(numbers.Select(number => number?.ToString()));
 
         return new AttributeValue { NS = list };
     }