spring cloud alibaba版本选择

https://github.com/alibaba/spring-cloud-alibaba/wiki/版本说明

Spring Cloud Version	Spring Cloud Version	Spring Cloud Version
Spring Cloud 2020.0	2021.1	2.4.2.RELEASE
2.4.2.RELEASE	2.2.5.RELEASE	2.3.2.RELEASE
Spring Cloud Greenwich.SR6	2.1.4.RELEASE	2.1.13.RELEASE
Spring Cloud Hoxton.SR3	2.2.1.RELEASE	2.2.5.RELEASE
Spring Cloud Hoxton.RELEASE	2.2.0.RELEASE	2.2.X.RELEASE
Spring Cloud Greenwich	2.1.2.RELEASE	2.1.X.RELEASE
Spring Cloud Finchley	2.0.4.RELEASE(停止维护，建议升级)	2.0.X.RELEASE
Spring Cloud Edgware	1.5.1.RELEASE(停止维护，建议升级)	1.5.X.RELEASE