Fix typo

Author: stephentoub

src/ModelContextProtocol/Utils/Json/CustomizableJsonStringEnumConverter.cs

@@ -7,7 +7,7 @@
 // NOTE:
 // This is a temporary workaround for lack of System.Text.Json's JsonStringEnumConverter<T>
 // 9.x support for JsonStringEnumMemberNameAttribute. Once all builds use the System.Text.Json 9.x
-// version, this whoe file can be removed.
+// version, this whole file can be removed.
 
 namespace System.Text.Json.Serialization;