Spring Boot版本1.5.7.RELEASE升级到2.5.14

1. 内置tomcat升级，从8.5.x升级到9.0.x
2. flyway升级，从4.2.0升级到5.2.3，配置：

flyway.enabled=true
flyway.baselineOnMigrate=true
flyway.locations=db.migration

修改为：

spring.flyway.enabled=true
spring.flyway.baseline-on-migrate=true
spring.flyway.locations=classpath:db/migration