refactor: 调整flyway

backend/src/main/resources/db/migration/V31__message_task.sql

@@ -4,7 +4,7 @@ CREATE TABLE IF NOT EXISTS message_task (
     event     varchar(255) NOT NULL COMMENT '通知事件类型',
     user_id   varchar(50)  NOT NULL COMMENT '接收人id',
     task_type varchar(64)  NOT NULL,
-    webhook   varchar(255) NOT NULL COMMENT 'webhook地址',
+    webhook   varchar(255) COMMENT 'webhook地址',
     CONSTRAINT message_manage_pk
         PRIMARY KEY (id)
 )

backend/src/main/resources/db/migration/V34__modify_message_task_webhook.sql

@@ -1 +0,0 @@
-alter table message_task modify webhook varchar(255) null comment 'webhook地址';