fix 修复 sql书写错误

script/sql/update/update_5.4.1-5.5.0.sql

@@ -57,4 +57,4 @@ create table flow_instance_biz_ext (
 )  ENGINE = InnoDB COMMENT '流程实例业务扩展表';
 
 ALTER TABLE `test_leave`
-    ADD COLUMN `apply_code` varchar(50) NULL DEFAULT NULL COMMENT '申请编号' AFTER `tenant_id`;
+    ADD COLUMN `apply_code` varchar(50) NOT NULL COMMENT '申请编号' AFTER `tenant_id`;