[logback-dev] Upgrade slf4j to 1.7.30 for 1.2.x?

Hi, What do you think about upgrading slf4j from 1.7.25 to 1.7.30 for version 1.2.x? According to maven for logback-classic, seems like the latest stable version in 1.2.3 which was released nearly 4 years ago. I can help upgrade this as well, however, this will be my first PR for this project; guides are welcomed. Kind regards, Kris