fix(ai): Make DefaultToolCallResultConverter work with GraalVM

Author: ThomasVitale

Diff for: arconia-ai/arconia-ai-tools/src/main/java/io/arconia/ai/tools/execution/DefaultToolCallResultConverter.java

@@ -10,6 +10,8 @@
  */
 public class DefaultToolCallResultConverter implements ToolCallResultConverter {
 
+    public DefaultToolCallResultConverter() {}
+
     @Override
     public String apply(@Nullable Object result, Class<?> returnType) {
         Assert.notNull(returnType, "returnType cannot be null");