[update] 资源上传时，没有选取文件上传值为数组导致报错

yudao-module-llm/yudao-module-llm-biz/src/main/java/cn/iocoder/yudao/module/llm/controller/admin/learningresources/vo/LearningResourcesSaveReqVO.java

@@ -1,5 +1,7 @@
 package cn.iocoder.yudao.module.llm.controller.admin.learningresources.vo;
 
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.deser.std.StringArrayDeserializer;
 import io.swagger.v3.oas.annotations.media.Schema;
 import lombok.*;
 import java.util.*;
@@ -25,6 +27,7 @@ public class LearningResourcesSaveReqVO {
     private Long fileId;
 
     @Schema(description = "文件URL地址、视频封面图", example = "https://www.iocoder.cn")
+    @JsonDeserialize(using = StringArrayDeserializer.class)
     private String fileUrl;
 
     @Schema(description = "文件名称，视频链接",example = "https://www.test.com")