add default constructor (#6780)

Co-authored-by: Nhonghuo.zw <honghuo.zw@alibaba-inc.com>

dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/utils/PageInfo.java

@@ -51,6 +51,10 @@ public class PageInfo<T> {
      */
     private Integer pageNo;
 
+    public PageInfo() {
+        
+    }
+
     public PageInfo(Integer currentPage, Integer pageSize) {
         if (currentPage == null) {
             currentPage = 1;