fix: database schema in mysql 8.0 error

Author: jianggang

src/main/resources/db/migration/V35__add_toggle_publish_time_fields.sql

@@ -1,2 +1,2 @@
-alter table targeting add publish_time datetime not null DEFAULT CURRENT_TIMESTAMP after `deleted`;
-UPDATE targeting t SET publish_time = (SELECT (case when count(id) > 0 then tv.created_time else now() end) from targeting_version tv where tv.organization_id = t.organization_id AND tv.project_key = t.project_key AND tv.environment_key=t.environment_key AND tv.toggle_key=t.toggle_key ORDER BY tv.version desc LIMIT 1)
+alter table targeting add publish_time datetime after `deleted`;
+UPDATE targeting t SET publish_time = (SELECT (case when tv.created_time != null then tv.created_time else now() end) from targeting_version tv where tv.organization_id = t.organization_id AND tv.project_key = t.project_key AND tv.environment_key=t.environment_key AND tv.toggle_key=t.toggle_key ORDER BY tv.version desc LIMIT 1);