Add missing validate check (#2372)

This branch was missed when adding the validate config

Author: rayokota

src/Confluent.SchemaRegistry.Serdes.Json/JsonDeserializer.cs

@@ -251,7 +251,7 @@ public override async Task<T> DeserializeAsync(ReadOnlyMemory<byte> data, bool i
                         {
                             string serializedString = jsonReader.ReadToEnd();
 
-                            if (schema != null)
+                            if (schema != null && validate)
                             {
                                 var validationResult = validator.Validate(serializedString, schema);