fix: update deprecation link to FunctionCallback.builder()

Author: garethjevans

spring-ai-core/src/main/java/org/springframework/ai/model/function/FunctionCallbackWrapper.java

@@ -40,7 +40,7 @@
  * @param <O> the output type
  * @author Christian Tzolov
  * @author Sebastien Deleuze
- * @deprecated in favor of {@link FunctionCallbackWrapper.Builder}
+ * @deprecated in favor of {@link FunctionCallback.Builder}
  */
 @Deprecated
 public final class FunctionCallbackWrapper<I, O> extends AbstractFunctionCallback<I, O> {