Update src/Microsoft.OpenApi/Models/OpenApiSchema.cs

Co-authored-by: Vincent Biret <vibiret@microsoft.com>

Author: adrian05-ms

src/Microsoft.OpenApi/Models/OpenApiSchema.cs

@@ -437,7 +437,7 @@ private void SerializeInternal(IOpenApiWriter writer, OpenApiSpecVersion version
             });
 
             // enum
-            var enumValue = !string.IsNullOrEmpty(Const) && version != OpenApiSpecVersion.OpenApi3_1
+            var enumValue = !string.IsNullOrEmpty(Const) && version < OpenApiSpecVersion.OpenApi3_1
                 ? new List<JsonNode> { JsonValue.Create(Const)! }
                 : Enum;
             writer.WriteOptionalCollection(OpenApiConstants.Enum, enumValue, (nodeWriter, s) => nodeWriter.WriteAny(s));