feat:flyway修改

backend/src/main/resources/db/migration/V41__modify_message_task_set.sql

@@ -0,0 +1,3 @@
+alter table message_task
+    alter column create_time set default 0;
+

backend/src/main/resources/db/migration/V41_modify_message_task_set.sql

@@ -1,2 +0,0 @@
-alter table message_task
-    add create_time bigint(13) default '0' null;